Because that's how towns and counties have done things like, forever (self-determination in government being the protected principle),
I just have to point out the irony here. In 32 States since 1998, voters have used the "protected principle" to "self" determine that marriage is only for heterosexuals. Clara...? Do you support self determination?
Now you're saying that the First amendment Does not apply to state or local governments? I guess you now believe that local governments can establish religious practices in their schools and courts too.