I don't know if anything has changed with the dawn of HBOMAX but it always used to be that an episode of an HBO show wasn't available On Demand until the time it started airing.
Out in the Philadelphia suburbs, I do occasionally hear that accent and it makes me wonder if I've somehow stumbled into Baltimore.
To be fair to this show, you hear a variety of accents anywhere you go so I think anything close is permissible and still accurate.