Sometimes the invisible hand gives you the finger; I'm willing to wager that in a lot of these cases you end up with massive barriers to entry, and so once a company gets shuttered or pushed out competitively it will take years and years before a suitable replacement appears.
Not that I have any good ideas on how to make the subject better.
It would just weird me out. I'd arrange everything so that communal bills are paid proportionally, i.e. you make twice as much as your spouse, you pay 75% of the rent, and everything else stays separate.
Not that I have any good ideas on how to make the subject better.