The transformation of the South is remarkable. What was once a solidly Democrat region has done a 180% turnabout, fully embracing Conservatism. As you said, the states of the Confederacy where slavery once existed now are where worker and employee freedom now reign with common-sense Right to Work laws.
And since I'm about to turn 70, I've seen these dramatic changes all within my lifetime.
Part of that is because in the 70s and 80s (and later) when times got hard unions (which are historically based in what was the North) threw the southern plants under the bus when they were told “we need to lay off workers, tell us where we can”. The northerners chose to pitch the struggling Johnny-come-lately southerners first to save themselves rather than spread losses equally and they continue to do so.
They built themselves up a lot of ill will and Southerners are the type who will do something about it.