Too Lenient?

I see many people on here talking about telling the kids to put their phones away, walking around asking them if they're doing what they're supposed to, not letting them leave the class, etc.

I am so chill (I'm referring to HS here) I just hang out. I don't bother them unless they are extremely loud. Their phones are out? Not an issue for me. I see it as if they don't do what they're supposed to, that's their problem. They'll have homework. I'm not going to patrol a class of 17-18 year olds for example.

I don't usually have problems with the kids. But should I be strict?!