What astounds me the most about this whole thing is that the sort of hit testing involved here is a solved problem in UI, and has been for decades, yet there are still plenty of others here and elsewhere arguing about how it isn't. Even with those horrid rounded corners it's not hard, as shown in the article, which makes me wonder whether there is some internal fight between those who didn't want rounded corners (developers?) and hence tried their hardest to make it buggier, and those who wanted them (designers?), with lots of back-and-forth that eventually gave us this outcome. A disturbing amount of time and $$$ was probably spent on it, as is usual for any bureaucracy.
Mobile Safari has some horrific hit-testing for touches. There's plenty of places where touching near a control incorrectly snaps the tap to the control (sometimes with rather nasty usability consequences).
Ideally there should be some way to control the tapzone within CSS.
Last time I needed to fix the problem on a page I was responsible for it required adding an HTML element, which was far from ideal. I seem to recall I also had to explicitly add an onclick handler too (registering an onclick handler silently modifies touch behaviour on Safari - a nasty hidden side effect). There's some new badness with stealing taps in iOS26's Safari - ugggh.