I think the only legal protection you get from the US government is on the basis of race/religion and what not, as well as some of the original Union terms like 40 hour work week and overtime. Right to Work has to do with whether you are forced to join a union or not. And if not, then don’t get the supplementary legal protections of whatever is in the union’s agreement.

You become “fire at will” not because the law says so, but because you are not in a union. On the other hand, most unions will still protect nonunion workers.

I’ve never really heard of programmer unions though. Would be curious.