Corporate Users. My guess is, that almost any office job where you work on a Computer has Windows as OS. You have a license for your job. The license for home usage is bonus money to Microsoft.

They must do something, or Windows wouldn't constantly turn them back on with every other update.

and don't get reset the next update.

Do you think Microsoft wants to get sued by the EU?

Those opt-out work. Or at least in the EU they do.