When looking for questions about unions, I saw one from a 1994 Pew survey: are they "having mainly a good influence on the way things are going in this country or mainly a bad influence on the way things are going in this country." The question was never repeated, but it was part of an eight-nation survey. Here is a summary of the results for each country (percent positive minus percent negative). The survey recorded opinions in former East Germany and West Germany separately, so I show them both.
E. Germany +25
United States +5
W. Germany +5
The United States is fairly favorable by international standards. I expect that the unfavorable opinions in France and Italy were because strikes were more frequent there, and public opinion is usually negative about strikes (or any kind of disorder). I'm not sure about Canada--I'd have to check if anything special was going on in 1994. But American opinion being as positive as West German is a surprise.
The survey also asked the same question about other things, including business executives or management. The results:
E. Germany +19
W. Germany +11
United States +7
The United States is not unusual here: the surprises are Canada and France.
The full report can be found at the Pew Research Center website. It's not clear if the individual-level data have been preserved.