> A dirty room or a car is an inconvenience.

I too have no desire to buy food from strangers, but I also feel like the potential risks of room-sharing or ride-sharing aren't limited to cleanliness. In both cases you're implicitly trusting a stranger with your physical safety.

Speaking for myself, I think I'm more comfortable with the notion of ride & room sharing because I can maintain a greater (and quite possibly illusory) sense of control. Drunk or unreliable driver? I can get out. Sketchy apartment? I can leave, or prop a chair against the door. etc.