I am English but moved to the Bay Area a few years back and became friends with a union electrician from Alabama so this conversation comes up a little - it sounded like unions are supported in the south even if they look a little different. However I’m not American and am not certain about that at all :)

Does not seem like given a lot of the auto factories in the south are not unionized and multiple attempts to unionize them failed because the workers reject them.

Then there was that famous failed attempt at unionizing the Amazon warehouse in Alabama? I think? Yeah there was a lot of shady stuff going down but it just does not look good among all the other failures.

States in the south have laws that neuter unions, and some that make unionizing for certain fields/roles illegal.

Unions might exist, but they might not have the same teeth they'd have in states with friendlier organizing laws.

Right to Work laws allow employees to make an individual choice whether to join a union in a unionized shop.

No one is forced to take a union job if they don't want to, those same laws break private contracts between unions and employers and force unions to represent non-dues paying employees.