I’d imagine this was at least in part a tool used for exactly these types of situations.
A business has a right to protect it’s interests too.
I don’t think people were forced to fill out the card favorably and then sign it.
As for unions, this involved their employment and I agree names should not be on their vote.
The NY AG lawsuit had this to say.
"Trump University instructors also asked that students complete evaluations in order to receive their Certificates of Competition for the course and 'pleaded for a favorable rating so that 'Mr. Trump would invite [them] back to do other retreats.' Mentors compelled students to complete the non-anonymous evaluations in their presence, filled out the forms themselves or pressured students into giving them higher scores or completing the evaluations before they had an opportunity to see if Trump University's promises would be fulfilled."