I think that a 9:30 to 10:00 curfew for teens is okey if the teen has some friends with them and are careful. They should also make sure that they have their phone with them just in case of emergency.
I think that teen curfews is a good idea if the teens don't stay out too late and don't come back too soon. If a parent makes their teens curfews too early, they might feel like they don't have enough freedom, but a parent should still be able to spend time ith their teen.
Although, if the state sets a curfew , the teenagers might rebel and break that law. Also, what if a teen has a late job? He/she might get arrested for making a little money.