What's missing here is the central conceit of Trek: that humanity grew up. We could have a utopia now if people would just stop being greedy little shits, and decided to embrace empathy and forgiveness. There's nothing stopping every single person in a modern conflict from dropping their weapons, but we still want vengeance and punishment. and I'm not saying I'm above that: someone kills someone I love, and I'm going to want blood. On paper I'm against capital punishment, but I know if I was faced with a war on my doorstep, bombs being dropped, my morals may not hold.

In Star Trek, they had WW3/the Eugenics Wars, and after that...humanity finally had enough. Never again, but for all the ills of humanity, in a way.

So very few people in the Trek world would actually complain about working a shit detail, because they're in it for the greater good. We saw in TNG episodes that randos from the 20th century could just waltz around the ship at their leisure, and how lax security is...because people just generally behaved well. Humanity really did bind themselves to a stronger social contract, if that's the right term.

As for needing ships: there seem to be plenty of civilian ships out there, from trading and light exploration to proper science vessels. Not all Starfleet, though the shows have focused on them. So I can only imagine there's plenty of opportunity for non-Starfleet folks to get out there.

Granted, DS9 pushed back on all this a little, as the Maquis are comprised of a lot of Federation members that went feral/colonial and don't hold themselves to the Federation ideals that seem to keep the rest of humanity and others acting in good faith at almost all times. Likewise still plenty of BadMirals out there, and they do show the Tom Paris-es of the world in some kind of prison, so it's not all roses, and could definitely be spun as drops of dystopia in a utopia, but we're also told (and have no reason to doubt) that it's all well-above board, humane, and focused on rehabilitation instead of punishment.

Also, all that said, I do wish it wasn't so hierarchical, but that's my anarchist streak flaring up.