It happens to that word (and that word alone) too much for it to always be a typo.
I remembered another such one: "sale" vs "sell"
In my part of Texas I see on Craigslist "for sell" all the time. I mean, sale is a noun and sell is a verb!
I guess with a thick southern (Georgia? Texas?) accent, sell is pronounced like sale -- but that just proves how invalid that accent is

When an accent causes you to have bad spelling, it's an objectively wrong, bad accent PERIOD.
But again, even if you grew up pronouncing sell "sale" because you're Southern, you still would have no issues IF YOU CRACKED A BOOK ONCE IN A WHILE. So you have to be illiterate/ignorant AND southern for the problem to happen. That's why I criticize. Not because someone was born a certain way, but because they are stupid.
There is no "R" in wash, for example. So while some Kentuckians say "worsh" and Midwesterners say -- "wash" -- who is right? Um, the Midwesterners. Who gets to say that? Well, the spelling of course!