It’s not just their immediate living environment though is it?
When I lived in a HMO (3 bed terrace with dining and living room converted to bedrooms) , we had a cleaner that came every 2 weeks and cleaned the communal areas. Of course it didn't go two weeks between cleaning of kitchen surfaces or floors. Some of us had higher standards of cleanliness and others were lazy or filthy. Not washing around the bath and leaving hair in plughole catcher to build up.
When the cleaner didn't come because of lockdown the letting company sent us cleaning items in the post and we cleaned up collectively, but this wasn't without some confrontation after a friendly request to the slob to take part.
I won't go on anymore, but the point is that the letting company didn't provide the cleaning service as a kindness out of their own heart. But partially to maintain a peaceful environment and prevent social tension.
Now imagine you have 400 people in cramped accommodation in a social environment that is exclusively adult male and has a social fabric that is a blend between a refugee camp and a prison. Some might take pride in their accommodation and keep up cleaning, others might not give a fuck, and some might bully others into doing it for them.
Unlike the military living in barracks, there is no rigid hierarchy to enforce order and shared standards of hygiene.