Reading this, I wonder about all the UIs that I come across today and feel like they're usually on a scale from flawed to awful (see also: store reviews of software, especially after an update). Not being from the software development world, can anyone who is confirm whether this type of user testing still takes place at all? Or is it perhaps confined to big redesigns, specific user groups (like beginning computer users, even for developer tools like vmware), or other such constraints?

Edit: reading further, this is a great example: "Separate UI for Beginners [...] [various problems mentioned] [...] For these reasons and others, we abandoned the idea". These reasons translate directly, one-to-one, to Android's simple homescreen variant that my grandma kept finding somehow, clicking on, and then not being able to use various things on her phone anymore. Nor getting more comfortable with the proper UI. Nor was it consistent with other apps. Android added this feature when, a decade earlier, it was already spotted (long before release, I should note) that such a variant wouldn't help people at all. This doesn't appear to have been thought about or tested in the real world, and I think Android is the most-used OS on the planet. (Not sure if all vendor's shells have this feature as well, but I'm fairly sure it was stock android or at least commonly implemented a few versions ago.)