As jrmj notes, phone plans with tethering aren't as common and often come with strings attached.

I use my phone in coffee shops that don't have [acceptable] WiFi. The main drawback is needing to be mindful of phone battery in addition to the laptop battery.

That being said, it's a great resource when you need a space to work at 11am-2pm (when all of the WiFi-offering spots are filled). There are a couple of local coffee shops with no WiFi, that don't forbid laptops – they're usually empty during peak hours.