But also custom date pickers are the most broken thing you can find everywhere. Browse with a combination of browser/phone the developer didn't test, and you can't pick even the most basic single date. The most blatant are the fancy range pickers, instead of two date picker boxes: I have been pushed to a desktop browser because the mobile renders half of it off-screen, or don't hold open after tapping the start date, or works by dragging but breaks on single taps...
Yep. I've also seen a datetime picker (in a log viewing tool) where adjusting time from keyboard is nigh impossible: you have "12:30:00", with the cursor right after the "30", and want to make it "35", so you press [Backspace] — nope, deleting a digit would make an invalid time, so the component undoes it. You press "5", but inserting yet another digit would also make an invalid time, so the component undoes it. You have to text-select the zero, and then press "5" to overwrite it... and you have to do it digit-by-digit, because you can't replace two digits at once with a single key press. Amazing.
It's a lose-lose situation, honestly.