Real Estate Agents and Builders to stop using the terms “master bedroom” and “master bathroom”

Yes, they are. In my wife's secretary are a box of cards leftover from when I was a little boy which refer to me as "master". I think they were sent out as thank you notes for 1st communion or something, but I sure as hell know from the time I was 10 that they were in bad taste. I may pull them out and have a conversation with my daughter to contextualize how ingrained racism is or, rather, was in the south when I was little.
The term "master" when referring to young men has nothing to do with slave masters and that's certainly not strictly a southern or even American term.