Big no thanks to this.
If you hate where you work this much, improve yourself and work somewhere else.
Replacing at-will with "just cause", progressive disciplining, with criteria for performance improvement plans.
If you're three years into a career in tech (technical or not) and you haven't figured out that being PIP'd or indirectly told you're fucking up - making this language "nicer" isn't going to help anyone.
Adults don't give feedback in a transparent way and this is because they don't want to look discriminatory. Modern employment and HR policies have done great things, but they've made the waters for this kind of communication even more opaque and pushed incentives that way as well.
Being unable to effectively communicate in a competitive professional environment as an adult and unionizing to solve this problem is at best juvenile, even worse when you think about long-tail consequences in terms of babying future hires.
As someone who previously worked at Amazon and found it shitty, Amazon is a stupid point of comparison for unionizing in tech because it's a shit-show run like a hedge fund. However, as a heuristic, people who've spent more than two years at any kind of Amazon should be avoided IMO.