That seems like a pretty sweeping generalisation of the North and South. I'm aware that I'm responding to anecdotal evidence with an anecdote myself here, but I

That seems like a pretty sweeping generalisation of the North and South. I'm aware that I'm responding to anecdotal evidence with an anecdote myself here, but I come from a fairly small Southern town myself, and I've been harassed here before for "sounding foreign" (my family are Irish, so my accent is a little strange, despite living in England for my entire life). Conversely, having moved to the North for university, no-one's ever remarked on my accent. I don't think this is necessarily a regional thing.