And yes, I know not all men do this but in my experience it is always men that do it!
I work in a professional job, and speak many times a day to people in senior positions in businesses throughout the UK. I have an accent from a city in the UK that's probably quite a distinctive accent.
At least once every single work day, I will get at least one male customer on the phone who, when I call them, mimicks my accent in their initial reply to me when I say hello and introduce myself. These are different men all the time; I don't have regular customers as such.
It even happened to me at passport control at a UK airport recently. The man scanning our passports asked where we'd been and why we'd been there. I replied and he then mimicked my reply in my accent.
AIBU to think it's fucking rude and disrespectful?