Ok, so the fact that the USA has no laws for severance is the problem, not the fact that companies who pay severance above and beyond what is required of them comes with strings attached. If severance was legally mandated people could tell the company to pound sand when they push an exit contract on you.

It blew my USA colleagues when I told them I can take over a year of legally mandated parental leave and there is nothing the company can do about it.