I don't think the Safari "swipe the URL bar to switch tabs" example is unintuitive. There is a strong hint at their swipeability because you can see the neighbouring tabs poking out on each side. I remember discovering this almost immediately when it was introduced!
(It's perhaps slightly less intuitive that you can also swipe the bar UP to access the tab switcher interface)
Hmm. I tried it on iOS Chrome and iOS Firefox. Works in Chrome (but it's not as obvious as in Safari because you don't see the adjacent tabs at the edge of the screen) ... but curiously not in Firefox.
(It's perhaps slightly less intuitive that you can also swipe the bar UP to access the tab switcher interface)