That's because, in the US, it's all true, historically. Auto unions were a big reason why Detroit's automakers were so uncompetitive against the Japanese automakers in the 80s; autoworkers got ridiculous pay for menial work, which is why Detroit moved a lot of their production to Mexico and Canada, and other automakers moved to Southern states where unions didn't exist.
The simple fact is that unions in the US in the latter half of the 20th century and beyond were nothing like unions in Germany, where by almost all accounts they seem to work out extremely well.
>Most people in Europe may not actively be a part of a union, but they normally recognize them as beneficial entities in the labor market
Yes, in Europe that's true. In America, it just hasn't been the case. It's just like public transit: in Germany, trains and subways are fantastic: they're inexpensive, clean, and efficient; whereas in America, they're an utter disaster: dirty, expensive, constant maintenance problems, and just a miserable experience. Try riding the subway in Munich, and then riding the subway in NYC or DC; there's just no comparison. The problem isn't that subways are bad, it's that subways in America are bad. Same goes for unions.