Let us suppose that people in the workforce can be categorized into those that need a compelling reason to leave a job (Group L) and those that need a compelling reason to stay in a job (Group S).
What would the benefits and retention strategies of a company predominantly employing people in Group L look like? Economics suggests that the company employing Group L employees would reach for the lowest common denominator in terms of benefits. The company would cite "best practices" in their industry to justify expending the least amount of money possible: the most basic health insurance, minimal vacation, and least flexible work hours, etc. There would be no financial incentive to do anymore than the least they had to do to keep their Group L employees. In fact, if they wanted to get rid of Group L employees, they would have to provide the compelling reason for them to leave, for example, layoffs. The company wouldn't have to worry about retaining Group S employees, nor would it have to worry about getting rid of them. They would likely have already have left.
Companies employing folks from Group L have it easy: they just have to make sure they don't give them a reason to leave. Except when they want them to leave. And my guess is that most people in Group L have similar reasons they would find compelling to leave.
What would the benefits and retention strategies of a company predominantly employing people in Group S look like? It would have to go out of its way to offer crazy generous benefits that were so obviously better than any of their competitors in order to retain Group S employees. Like free day care. Free food. Subsidized mass transit. Time to work on personal projects. Or they would have to put so much money on the table, maybe in the form of bonuses, so much that it might seem outrageous to those on the outside, that a Group S employee would be foolish to leave. Providing, of course, they didn't think they could get that kind of crazy money through other means. In which case, the outrageous bonuses aren't really a useful retention tool either.
Companies employing folks from Group S have it a lot harder. My guess is most people in Group S have different compelling reasons for staying. So the Group S company has to really scramble to keep their Group S employees.
Is it possible for a Group S employee to work at a Group L company? Sure, although the company probably has no idea why the Group S employee stays. The compelling reason for the Group S employee to stay may be something quite personal, even private. The management of the Group L company will be surprised when the Group S employee leaves, because from the Group L company's point of view, nothing has changed that could motivate the employee to leave.
Is it possible for a Group L employee to work at a Group S company? Maybe, and the Group L employee is probably amazed at how good they've got it. But the Group S company probably tries hard not to hire Group L employees. This could be done by placing all sorts of barriers in the interview and hiring process. Group S employees have to have a really good reason to apply for a particular job, even if it is with a Group S company.
I haven't said anything about the kinds of people that may be in Group L versus Group S. I have merely proposed a way in which you can decide which kind of company you work for. This probably says more about how your employer sees you than it says about you.