Why do some Northerners stereotype Southerners?

Why do Northerners say that stuff? NO, we are not hillbillies who live on farms (there is not a lot of farms anyway), NO, we don't say country slangs in every sentence, YES, we can read and write, NO, we don't sit on the porch and drink sweet tea, NO, we don't drink mint juleps (I don't even know what that is), NO, we don't only listen to country music (I hate country music), NO, we don't only eat grits, biscuits, and gravy, NO, we don't ride horses, and finally, NO, we are not poor! And I don't have any problem with Northerners, but I just don't particularly like their accents. Even really bad southern accents get on my nerves.