I wear poly ones that are spf50 all the time when I’m fishing so I don’t need to worry about applying sunscreen to large parts of my body multiple times a day.

I typically have really short hair, so I wear one with the hood on when it's chilly inside, but not so chilly that I want the heater on or want to wear a sweater.

My whole climbing crew has made the switch from hats and sunscreen to sunshirts. They fit under a helmet, and they feel less cancery than repeatedly slathering on some goo and crossing your fingers. It's one thing if you're free to roam about to a more comfortable area, but if you're stuck on belay duty on the sunny part of the face, you'll be happier with a sunshirt.

And then you're used to it, and you start wearing them elsewhere too, because why bother with lesser protection?

They may be more popular at higher altitudes than at the beach though. Beach folk have a bit more atmosphere protecting them.

Almost every serious fisherman that I know or watch on YouTube wears long sleeve SPF shirts with hoods.