Which is not the "everyone is doing it argument", but more "why does this need legal regulation now?". Why not before on web apps? The privacy implications look the same to me, but the point does not seem to be raised in the latter case.
This service is designed to produce user specific data. judging from what they record on websites (see docs, tldr everything) I'd be surprised if the iPhone version doesn't record GPS locations or what other apps you use.
I'm also not sure how commonly websites record data in this detail that also maps to specific users, but if it's common on websites its definitely news to me - and all the more reason to use stuff like Ghostery/Disconnect/Noscript. Do these have iPhone equivalents yet?
You expect a coffee shop's camera to track you, but you sure as hell don't expect your moka pot do that. Moreover, if it were doing that, you would've not bought it in the first place.
1) Network requests (and thus communication with a remote machine that can log those requests) is an innate facet of the web. You can't load a site without explicitly choosing to make a network request. An app, however, might have no innate reason to make a network request at all.
I think #1 is the most important, but also:
2) JavaScript can be disabled.
3) HTML/JavaScript and browser network requests can be reviewed. Mobile applications are almost completely opaque to users.
4) Cookies can be blocked to reduce tracking surface.
5) Web analytics and cross-web tracking is already something people are concerned about, resulting in the introduction of do-not-track and similar.
Desktop apps have almost always explicitly asked permission before tracking users, whereas the web community seems to have brought to mobile a blasé approach to privacy and user respect.