I don't see how Avril and Taylor make similar music tbh what are yall talking about
Before LA Reid decided to make Avril a faux punk pop girl, she sang and wrote country-pop music. Their music in very interchangeable. One clear as day example is how Shake It Off sounds like it was inspired structurally by Girlfriend. They both have the "Hey Mickey" beat, and that same rap/sung verse for the bridge.
Any song off of Speak Now and Fearless sounds like something that could've been on Let Go. The production is pretty much identical. Keep in mind Taylor Swift isn't actually from the South, and doesn't have a real southern accent - she sorta faked it during her "country" eras. Taylor Swift is as "country" as Avril was "punk". They're both posers, but Taylor Swift was marketed 100% better and had a much stronger team. When she sold out, nobody gave a f*ck because she made the transition slowly. Avril's however, was completely sudden and out of the blue and most of her fans were the "I'm not like the other kids" teens so when she stopped being "dark" everyone jumped ship.
Not to mention, even their voices sound alike at times.