Because we (or perhaps I) apply different standards to different situations - a bad car driver that causes accidents are accepted as facts of life, whereas a computer driven car is expected to be far safer and have no fatalities.

Personally I find it useless to see a machine as a colleague when it is not better in any way then a colleague, in the same way I don't see a hammer as a very punchy workmate. If I want to have a conversation about something I'll go talk to a human, when I interrogate a database I expect it to be better then a random human.