I don’t see why some don’t find the idea of Finn working sanitation while stationed at the base to be so unbelievable. Aren’t new recruits in real world militaries often tasked with menial jobs before they can rise through the ranks?
Do the Green Berets complete their Green Beret training and then get assigned to the Pentagon to take out the garbage?
Answer: No.
Also…sanitation in Star Wars…that’s what droids are for.
You must not be familiar with Military etiquette and protocol. As a U.S. Army veteran I can tell you that if it is part of your assignment or your told to, you do it no matter what rank you are. It’s part of the gig.