In many European countries parking is paid with a mobile app these days. Very few use parking meters.

I encountered this in the US a few days ago. It made me angry because it locks out those who don't have a smartphone or aren't willing to install Yet Another App.

I moved on and found a different lot.

It’s relatively common in the US as well but having backup is important for visitors, when apps need a forgotten password rentered etc. Way too many ticketing and other systems are way too unfriendly for the occasional user as it is without requiring that an app has to be used.