It's interesting that sometime in the 2000s, there became an expectation that coffee shops became a workplace. I can't think of another food service business where the expectation is that anyone can come in, buy a single item, demand the wifi password, and work from that space for multiple hours.
Cafes that wanted to ban laptops are free to do so and always have been. Generally people who work on laptops come in during periods when the cafe would otherwise be fairly empty (10-5 weekdays). This is an additional source of revenue to the cafe that doesn't interfere with their core revenue streams - the morning takeaway coffee rush + weekend brunchers.
A local cafe near me bans laptops on weekends. Another one bans laptops on weekends unless you sit in a particular area. Another one has a special laptop area. These are all successful cafes.
I have a feeling that the cafes who prohibit laptops outright are mostly just canceling a stream of revenue. That's certainly their right, but it's probably not what is best for them.
No one cares about being polite at Starbucks, but I would say the expectation at independent shops is still to purchase something periodically. Not everyone follows it. I don't see many independents limiting access with expiring authentication or codes given at purchase anymore. In the US, many attempting to do that don't seem to even know they're also running a free xfinity hotspot...