There also is no point of collective bargaining for them as they don't have centralized skills or a centralized set of employers like most union jobs do.

If you think "software engineers" don't have skills as comparably fungible as carpenters or factory works either you're not a programmer or your code is hot garbage.

It's also irrelevant with regards to unionization. Actors,.writers, lawyers, and doctors all have unions, and the last two are so old and so pervasive that it's easy to mistake them for something else.