I use fish because I have better things to do than tweak my shell configuration and debug shell plugins.
When I tried oh-my-zsh and prezto (I think?) they came with tons of plugins that performed badly and made it hard to get things done (specifically, they ran git status synchronously on every new prompt, which does not work well in a moderately large repo). Fish had similar features but wasn't horribly slow, so I use it.
Anecdotally, I see them all the time in my neighborhood, and they seem much more attentive to pedestrians and stop signs than regular drivers. Drivers in this neighborhood act like they own the place even though there's probably an equal number of pedestrians out at any given time.
I've also seen one of them fail to pull over when an emergency vehicle was behind it, so I buy that they are causing some problems.