Amazon fails to understand that it is currently a worker’s market in software engineering so they are the ones who have to convince engineers to work there.
I get pinged by Amazon recruiters almost every week right now, and once I discovered the assessment was 2.5 hours during my last job search, I had trouble finding the time and energy to fit it in amongst all the other job search requirements I had to do.
Ended up getting so far along the process with 6 other companies that I just didn't bother to take it. Still ended up with a job offer with a 60% bump in pay and what seems like a better environment than Amazon would have been, without any threats to force me back into the office or needing to relocate.
Lots of equivalent paying companies in Canada now, yet alone USA.
None of this is a reflection of the value of unions from the employees' perspective. But it's important to realize that unions are one of the instances where the employees' and employers' interests are not aligned. So, emailing a recruiter and mentioning unions has only one possible outcome - none.