I swear the last time I went to the court house in Independence to pay a ticket, I put my laptop bag and phone in the scanner. I do remember seeing signs that said no cell phones in the court room and turned mine off. But maybe they are different there OR they changed it since then. (Or I could be misremembering, but the fact that I recall that place as “weird” was because I hadn’t had to do it in the past.)
Ironically, as I was at the counter a guy came up with a cellphone, but I assumed he was a lawyer and they make exceptions for them.
Doh - making assumptions!