No one WANTS unions. We would like to be dealt with individually in a fair manner. But when tithe business you want to employ you has an entire department intended to get you to sign on for the smallest cost possible... Well... Some union starts to look like a pretty good idea. Even if it does end up causing a lot of grinding since common sense goes out the window once lawyers and contracts come into the picture.
1) For a long time, there was no "institutional" left in the United States; so in the US - liberalism was seen as the "left". This is slowly changing now...
2) The tech crowd wants really to believe to be progressive (because they work on "progressive" technologies); but in fact, I never saw so many real life liberals like among tech workers.
It's an interesting combination that doesn't fit super-well into America's dominant left-right political axis.
Liberals are often right wing parties in other countries. Basically you have a scale from socialism where everything in your life is dictated by social contracts to liberalism where almost nothing in your life is dictated by social contracts. The left in the US calling themselves liberals is kinda like the north korea calling themselves "democratic people's republicc". Their only liberal agenda is freedom from the Christian social contract.
Eg. Support gay rights and environmental causes, but don't really give a shit about poor people.
https://en.wikipedia.org/wiki/Political_spectrum#Greenberg_a...
My wife has worked the same job in and out of unions. She didn't want a union, it was a drawback for her. Her union job seems okay. Some things are better, some are worse. They've got some absolutely asinine policies that everyone hates that don't change and haven't changed for a decade or more despite the union "power".
Also, her job requires a masters, soon to be a Ph.D, and still pays less than most of tech (though it pays very well).
And of course because PART of the industry is unionized, it is impossible to say to what extent non-union jobs are free-riding on the "benefits" of a union.
That's an interesting assertion that you seem to be accepting as universally axiomatic.
(... or perhaps, a self-referential definition. Maybe a company isn't "massive" until one observes behaviors that suggest the company is purposefully acting counter to employee quality-of-life wishes?)