Earlier quoted context omitted.
Because they’re betting, with a good deal of historical justification, that they can have their cake and eat it too. US has unfortunately been union-unfriendly since Reagan.
The US has been union unfriendly since the 19th century when union leaders were regularly assassinated, and in the 20th century when striking workers were aerially bombarded and killed.
This got further cemented when the USSR was formed, and it actively supported many left winged militant organisations in europe. This was used as leverage by trade unionists and social-democrats to demand further rights (or else the militant forces will get into power and things will end much worse for the establishment).
This dynamic only really changed right before world war 2, when stalin (and other USSR leaders) focused on a policy of "socialism in one country" instead of a the dogma of a worldwide workers revolution.