There's also big in-group out-group thinking going on here. People generally see members of the in-group as individuals like themselves, and the out-group as some kind of monolith. They have some empathy for the in-group but none for the out-group.

If a driver runs a stop sign, it reflects badly on that driver. If a cyclist runs a stop sign, it reflects badly on ALL cyclists, etc. It works the other way around too.