One for Bitt, probably:

More and more recently, I've been seeing people writing 'that', when they mean 'than'. See today's example from the qmail mailing list:

Thanks for a better example than the one that popped into my head! Folks
who use various return addresses, but are forced by their ISP to use
in-domain envelopes, do the same thing--but that's less significant that
the mailing list traffic out there.

This paragraph uses both 'than' and 'that'.

My question: is this just an increasingly prevalent typo, or is there some dialect of the English language in which this is allowed, and of which I'm not aware?