Fleas?

My cat has fleas - I haven’t seen any and she doesn’t seem itchy at all but I found flea dirt on her. I treated her with topical flea medication and I’m going to bathe and flea comb her tomorrow, but I can’t eliminate the source of the fleas because two of my roommates work in home care & they both have clients who have no pets but whose apartment buildings are entirely infested with fleas and there are basically no tenant rights where I live so there’s no course of action to treat the apartment buildings. We have them change clothes and quarantine their work stuff as soon as they get home but I guess it hasn’t stopped the fleas from being brought home and it never will. But obviously they can’t quit their jobs or we won’t have a home to have fleas in & moving isn’t an option because of insanely high cost of living where I am. I work 6am-6pm four days a week and just don’t have the time in a day to vacuum every soft surface of our very large house every day.

Any advice on controlling the infestation at least until I can move in 2-3 years?

(ETA already called her vet and they said they can’t do anything more than give us the topical flea treatment once a month).