I wouldn't look to SAG as a good example. The format of that industry is very different from most "typical" jobs, specifically tech work. I would also suggest looking at the the recent SAG healthcare fiasco.
Yes, the idea for health benefits was great. But now we see that the SAG is just like corporation - cutting benefits because the highly paid big wigs don't want to pay for them.
The film industry has way more talent supply than the employment demands, which naturally suppresses pay. The guilds/unions are a way to increase scarcity to maintain pay and ease hiring.
The tech industry has much less talent supply and much much much more employment demand. Tech might be better modeled after high skilled trade unions (which have a labor shortage) than the comparatively lower skilled film/auto/factory unions (which have a labor surplus).