For a while after the invention of the warp drive, ships could "only" travel at the speed of light or slightly above (not above warp 5), meaning that it could take generations to reach other stars.
Remember, civilian vessels only get "Last Generation" proven Warp Drives that are proven to be reliable with solid test trials with proven "Track Record of MANY LY (Light Years)" tested & validated on the engines before going into mass production for civilian purchase.
So they're usually, "At Best", 2 generations behind whatever StarFleet is in the process of testing.
StarFleet is usually testing the "Latest & Greatest" Warp Drives.
Just look at ST:ENT & Travis Mayweather.
His family was on the
J-Class ECS Horizon.
That was a "Warp 2 Maximum" speed freighter with Warp 1.5 when fully loaded with Cargo.
It was a "OLD Cargo Freighter" that he grew up on.
Warp 3 engines were most likely what would've been considered a "Top of the Line" civilian Warp Engine that can be attained.
At the same time...
Travis Mayweather was the Chief CONN officer on the NX-01 USS Enterprise.
The NX-class was testing the Warp 5 engines.
The rest of Earth's StarFleet were just getting Warp 4 engines in mass production across the regular United Earth's StarFleet.
The
USS Franklin (
Freedom class) that got stranded on Altamid was a Warp 4 StarShip of it's era for UE's StarFleet.