I agree and disagree, you can't target everything, but most (not shit) devs will target at least Safari - 1 or 2, simply because the iPhone market is too good to miss out on. And Safari being, well, Safari, means targeting that is a pretty safe bet for anything else.

I target IE6 and it just works everywhere

De facto they do because functionality built three years ago and tested then is running along side functionality they built yesterday and tested on today’s Chrome.

People also do seem to test on iOS Safari because that pain in my ass needs special care on my software. So if a site works on it they either got lucky or tested on an iPhone. It’s generally only other people’s weird tech demo stuff that doesn’t work.