Case in point people in some states are given a day or two to back out of a new car sale presumably due to high pressure tactics used at dealerships.
I guess the idea is, how does the fact that the employer can walk up to you at any point regardless and say "walk out the door" interplay with other facts and laws? Are you just constantly under duress? I would assume not, since you also have the mirrored right to just walk out the door of your own volition at any point.
I can see logic the in interpretation that this arrangement basically results in the constant ability to reconsider the employment agreement: "If you don't like it, you can leave at that very moment. Otherwise, you are bound to it."
The problem as I see it is that the power of At-will employment rests mostly with the employer. It is asymmetrical. Most people could not afford to lose their job without serious financial difficulties, and if they disagree with some new policy in principal, then the only choice is to resign, be forced out, or continue working under the new policy.
Most employees will never be in a situation where they can say "Screw you, I'm not signing that". There's too much at stake. There are multiple reasons for this:
The job they hold does not pay them enough to save and emergency fund.
They don't practice good financial judgement.
They are ignorant of the risks of at-will employment.
They are in their comfort zone and don't want to push back.
They signed a non-compete agreement.
By the same token most employers can't afford to have key people walk out the door without serious financial difficulties. Anyone who thinks this is asymmetrical has never been tasked with making sure projects are staffed. Most technical people have left an employer in the lurch at some point.
Even key employees can be replaced if properly managed.
If they are a key employee, they bide their time, plan, and locate a suitable replacement candidate. Once the replacement is up to speed, they let the replaced employee go. I've seen this happen a a lot in the companies I worked for.
I don't want to press my opinion too much. But I find it very frustrating when I hear people claim they are unconditionally in favor of "at will employment" and then claim they think some of the consequence are unfair and should not be allowed. I sincerely wish such people would revise their statements and say they are not fully for at will employment.
That seems like a useless and counterproductive interpretation to me.