Not so helpful advice

Why is it that when you tell people about a software, hardware or online problem, you inevitably get one (or more) of four responses, none of which is helpful:

1. It works for me.
2. I've never had that problem.
3. It shouldn't do that. Are you sure that's happening?
4. Have you tried [obvious basic operation]?

That's basically the equivalent of telling people my car won't start, and getting the responses:

1. My car starts. (Yeah. My car's broken. Not yours.)
2. My car's always started. (Guess what? Mine always started too, until it went wrong.)
3. Your car should start. Are you sure it's not starting? (Yes, I'm pretty damn sure.)
4. Have you tried turning the ignition key? (Uh, yes. How do you think I normally start my car?)

All obviously useless responses. So why do we treat computer-based issues so differently?