What’s the point?

So my mum and older brother teach horse back riding on our farm and we get a lot of young teenagers coming. This happened last year in September and for context my family current have 10 horses and 2 of them people outside the family can’t ride. 1 is my horse dusti and the other is our stallion max.

So last year about a week after school started for the year mum was doing lessons and a girl walked into the stable and saw me getting dusti ready to ride but I wasn’t wearing any riding gear I was in my farm clothes that make me look like I just ran through a a swamp. As soon as she saw me started demanding that I stop touching her horse. It really confused me so I just stared confused at her. She started saying that I shouldn’t be here as it’s only for people who take riding seriously and can afford to ride them. Every time I spoke she cut me off to continue having ago at me. She then said that she knew the family for years and that my mum was like a aunty to her.
After that she actually let me speak and I just said you do realise I’m her daughter don’t You? She didn’t believe me so I told her to go ask mum her self.

She left the stable and I saw her after I got out with dusti. She avoided looking at me so I rode up to my mum saying loudly “hi mummy can I join today” which normally I don’t ask I just join anyway.

I really don’t get why people lie like that. It’s so pointless