1. you realize that in many parts of the US, they're not actually public utilities? PG&E is privately owned, for instance is a publicly traded for profit company.
2. Water and electricity are public utilities because they're a natural monopoly. It doesn't make sense for 3 different water/electricity companies to lay 3 sets of pipes/wires to serve one city, so we let one company do it. Needless to say, the same does not apply to shelter.
Edit. I would like to provide more information but it is such a complicated and broad topic that I could do it justice but I recommend looking into it. Just the various tariff schedules are interesting to read.
2. Water and electricity are public utilities because they're a natural monopoly. It doesn't make sense for 3 different water/electricity companies to lay 3 sets of pipes/wires to serve one city, so we let one company do it. Needless to say, the same does not apply to shelter.