I've seen this from a couple of VP/SVP level execs at companies I've worked. My pet theory is it's some kind of weird "My time is too important to even use the shift key" signal. They probably add up the cumulative amount of time they would spend using the shift key and multiply by their compensation and realize they could buy another car if they just optimized that useless key out of their lives.

So you know that they are rule and norm breakers, no rule too tiny to be broken and skipped in the name of productivity/health/insert-hot-thing-of-the-day

Oh that’s an interesting source I haven’t considered. It is rather stylistic.

Unlikely. They are separate settings both on iOS and Android.