I don't think you can compare a Star Trek 24th century society without money to a contemporary socialist government. The existence of replicators eliminates scarcity of resources, something that can not be said of 21st century economics.
Well, it doesn't so much eliminate scarcity of resources as it decreases drastically decrease costs of numerous resources across the board. Nonetheless, replicators still need raw matter to work from -- they don't just create something out of nothing, but work by, as it were, "re-distributing" matter into new forms. So not only do they need raw matter, but they also need the information to replicate new patterns -- which itself might end up being subject to intellectual property laws.
Capitalism certainly has its inequalities,
"Certainly has its inequalities?" Tell that to the millions of people in America who go to sleep hungry every day.
You can take physical currency out of the equation but you can't take economic inequalities out of the system. Just if you have no money, power becomes the only currency. Have you not heard stories from the USSR where the people who had access to luxuries were the people with the most connections? How is that any better than it being based on wealth? At least when it's based on wealth there's the possibility of social mobility for people who don't go along with the leadership.
If replicators are invented to solve scarcity, that would be wonderful. Until then, a free market system is far better than one that puts the government in charge of the economy.
Nobody here has advocated for the kind of authoritarian, statist socialism you are describing. It is as disingenuous to portray all forms of socialism as akin to Russia under Stalin as it would be for me to equate all forms of capitalism to Chile under Pinochet.
If you wish to argue against someone, please argue against what they are actually advocating for. Otherwise, the word is "Strawman."
Just, there should be education available to even out the playing field so it really is the hardest workers who make out the best.
This presumes that a nominally meritocratic society (and what is capitalism, if not in part a form of meritocracy?) can actually function in a meritocratic fashion. The problem with this is that reality does not bear the meritocracy out; a system that provides vast rewards for success and harsh punishments for failure only creates incentives for political and economic actors to subvert the rules of fair play. Recent history bears this out in industry after industry, as those who benefit from a meritocratic industry find ways to rig the game to their own and their allies' benefits, thus reinforcing preexisting disparities and class divisions.
There is a reason that the term "meritocracy" originated in a satire that was designed to warn against such systems. As Christopher Hayes puts it in his brilliant Twilight of the Elites: America After Meritocracy: "He who says meritocracy says oligarchy."