It's basically saying that Thanksgiving used to be a real holiday where almost everything was closed or closed very early, so that the workers would be allowed to have Thanksgiving off, have Thanksgiving with their families, etc. But now, with the popularity of "BLACK FRIDAY" and now "BLACK THURSDAY" savings, more and more stores are having their workers work all day (sometimes even after midnight, for 'black friday') on Thanksgiving rather than give them the holiday off.