Banning laptops is very common due to space constraints, when you're the kind of café that doesn't want people to stay forever. Even my university canteen bans laptops at lunch times. But the purpose isn't the same, here the idea is to create an environment for people to actively seek focus and peace.
https://www.npr.org/sections/alltechconsidered/2014/04/10/30...
https://www.theguardian.com/society/2018/feb/12/no-laptops-a...