Obi-wan Kenobi has been out of the loop for almost 20 years by the time he makes that statement. Clone Troopers were very good at what they did. Stormtroopers? Not so much.
If Kenobi had meant "clone troopers" he probably would have SAID that, yes?
They grab just about any human teenager who's spurned on by Imperial propaganda and then train them. The problem with the training is that they are trained to be a cog in the machine. No soldier matters in the Empire. You will use any one in your unit for your own gain and anyone can be left behind. You are a number. Nothing more. Same with TIE pilots.
If the soldiers don't matter, then what the soldiers DO is equally unimportant. We should be seeing widespread problems with discipline, focus and loyalty, troopers who will let just about anything slide for a bribe, troopers looting and stealing or shaking down locals for protection money.
Yet all through SW canon it's implied that the ranks of imperial storm troopers are very hard to infiltrate and that it's a waste of time questioning their loyalty to the Empire. They are at least as dedicated -- if not quite as competent -- as the clone troopers of the previous era. That implies they are both extremely well trained and also carefully screened. And even without the implication, much of what we've seen in their training process (e.g. the academy episodes in Rebels) echoes this: Imperial training is derived from the clone trooper training programs of the old republic, slightly simplified but aiming towards a similar standard of effectiveness. This means they aren't taking just anyone, and it also means they don't and can't consider their soldiers to be expendable; the kind of time and attention it would take to turn a disaffected kid into a fanatical suicide trooper necessitates a fairly small number of such troopers being deployed.
The Empire, for the most part, doesn't have a credible military power to fight.
Exactly. So they woudn't NEED a huge army of canonfodders intending to drown their enemies in bodies; the only enemies they ever fight are small local rebellions and crime lords. They'd have spent most of the pre-rebellion years in low-intensity conflicts: small, elite teams tasked with taking down insurgents, crime bosses and pirates. A single star destroyer would be enough to pacify an entire solar system, a pair of TIE fighters could lock down an entire spaceport, and a single storm trooper with a blaster could basically control an entire room and/or kill anyone in it if he had to.
OTOH, SW canon tells is emphatically that the death of Vader and Palpatine left the Empire scattered and squabbling among different factions of imperial loyalists. But there aren't a lot of loyalists in an army of cannonfodders, purely because absolute loyalty to the Empire takes a lot of time and energy to instill. Post ROTJ, you would see mass defections and desertions in over half the starfleet, and the Empire would basically cease to exist as a credible military force. This DOES NOT HAPPEN in canon, which suggests that Imperial soldiers are, for the most part, both highly disciplined and fiercely loyal to the Empire, which is how they're trained and depicted on screen and in novels.
Which means the Empire is going for quality of personnel, not quantity. This is definitely true of the Death Star, and is likely true of the TIE fighters as well.
The Imperial Navy can be run by the populations of loyal human worlds easily enough. To fill out all the Imperial-class Star Destroyers would take around 1.2 billion people.
Indeed. Now imagine if two thirds of those 1.2 billion people were utterly disposable,
and everyone knew it. If you're not deliberately screening out soldiers with rebellious or subversive traits, trooper rebellions would be relatively common, and the imperial fleet would be its own worst enemy. The Empire's creed is "rule through fear," but there are only so many inquisitors, and there's only one Darth Vader, and fifty guys with light sabers aren't all that useful when twenty thousand soldiers all mutiny at once.
Given how the Grand Army of the Republic worked...
... as an army of CLONES, with loyalty and military discipline literally programmed into them at the genetic level. That is the ONLY way an army that size could actually work, and
even among the clones there were desertions, defections, mutinies and betrayals. Discipline and loyalty among the Storm Troopers would be a thousand times worse.
When a galaxy spanning Empire (well effectively if spans more like half the galaxy with the other half being either Unknown Space or neutral systems) has several dozen human populated worlds with populations of around a trillion each
I think you mean a billion. A trillion people on a single populated world would make Coruscant look like a Milwaukee suburb.
The Empire's equipment though....is designed to inspire fear. AT-AT walkers are huge and terrifying. They are nearly impervious to weapons, by can be tripped up.
Which is another incongruity: the AT-AT walkers and even AT-STs are deployed in relatively small numbers. Assuming each one carries about 200 troops, then this means the Empire attacked the rebel base on Hoth with a force of about 600 to 1000 troopers plus a certain disgruntled former Jedi...
This, from a ship like the Executor, which is large enough to house something like 100,000 troops.
So why bother landing only 1000 totally disposable troops in a pack of armored vehicles that are otherwise impervious to weapons fire when you could just land 20,000 troops and have them bum rush the rebel lines in a sea of bodies and blaster fire? This, again, is my point: the background material heavily implies the Empire's main advantage is numerical superiority (quantity over quantity) but they never actually USE this advantage. And there, again, is the problem of the TIE fighters: you can't really tell me they're disposable and produced in massive numbers when, in A New Hope, the Empire only launches about 15 of them to defend
the entire death star. If they really had those kinds of numbers, they'd be able to swarm the rebel squadrons with ten-to-one superiority in the mother of all curb-stomp battles. Instead, they leave the defense up to what appears to be a single squadron of TIEs, and then when THOSE ships get wasted, it's down to Darth Vader and two wingmen.
They are in no way as good or as well trained as the Clone Troopers.
They actually appear to be about equal by literally every measure we've seen. Which is the source of this particular headcanon: if their performance is similar to that of the clone troopers -- who are genetically engineered and trained from birth to be soldiers -- then their training and indoctrination would have to be a lot more thorough than the clone troopers ever had. Hence their reputation: they're known to be loyal and effective, NOT corrupt and unpredictable.
Also TIE Fighters, in canon, have no shields, until the TIE Defender, which surprises the Rebels. I can buy them having heavy weapons to punch through Rebel Starfighter shielding, and allow TIEs to damage capital ships. It might even be why their weapons are green while the Rebel's are red. The Rebels are making due, with the Empire is using kyber enhanced weaponry.
Because fitting a disposable fighter craft with a completely disposable pilot with a weapon that uses one of the rarest and most valuable substances in the galaxy makes total sense, but fitting it with a shield generator -- which every fighter in history up until this point actually had -- doesn't.
Riiiiiiiight....
