Is it fair that I have to refer to her as "Ms Kaiser?" I am the adult.

So I am a 39 year old adult woman. My son's swim instructor is a 17 year old girl, her name is Farrah. Every time I call her by her first name, if the pool owner overhears he tells me I'm supposed to address the instructors properly. Personally it should be the other way around because she's the teenager and I don't think it's fair. I told her I will continue to call her Farrah and she just said whatever. I posted about this on Facebook and got mixed replies. Some people agreed with me and some people agreed that since she's the one in higher position in that specific area, she should be addressed as such. I still think it's incredibly stupid.

I also wanna add that I think the ma'am/sir, ms/Mr stuff in general is weird. You aren't owed respect but you can earn it.