Why is it that there is a cultural meme and expectation for an Employee to give notice to an Employer but, none the other way around? In fact, it largely happe

Why is it that there is a cultural meme and expectation for an Employee to give notice to an Employer but, none the other way around? In fact, it largely happens only because it's mandated by law. If I have loyalty to an organization and I don't want to hurt the people who keeping that organization running, then yeah, I'll give notice but, that is a gift. No one has ever told me that the company is going to be downsizing in two weeks; an exit interview and an escort out of the building is the only thing I've gotten.