Boy they do care, and they're pretty pedantic with every detail. The SBB app will allow you to buy regional tickets in ZH, but they check the time you bought the ticket, not just the time you requested it being valid from.
So if you see a controller, buy the ticket and then they see you got it a minute ago, you're getting a fine.
One time I had a day pass for Zone 10 in ZH, and then got an extension from a machine to get to Baden and back. When I got on the train, I realised the extension was wrong, so I went to the app and bought the proper one (essentially double paying my ticket).
2 minutes later an inspector lady comes in and gives me grief that I bought the ticket after the train departed. Showed her the printed wrong extension, explained and I just barely got away with it...
So they do care, and they care a lot.
Also from friends' experience (not Greeks funnily enough, but a rather broke Swiss; oh the irony
) multiple fines can also get "admin fees" similar to police and court admin fees, meaning hundreds of CHFs...