Why does my mum say that?

I sometimes want to make points about my school life and say that I have a hard time and then I think she enjoys to say stuff like stupid teenagers like you know nothing and you'lll never know what it's like to be an adult. I find this rude because I may be a teenager but I'm not dumb and I will know one day, I've never been disrespectful, gone out and not come home late, been irresponsible I've done great in my studies so I don't understand how she can boss me about and get into all of my business but then I cant even ask why she came home late from work (out of worry) she's constantly acting like she's in a competition with me and then wonders why i prefer school over home