Workers do not have the ability to choose whether to be a queen or not. That choice is made for them when they are raised. A larva cannot feed itself royal jelly.

No, from the point of view of their genes they are given a signal, they get to choose whether to obey it, i.e., a hypothetical mutation that causes the larva to develop into a queen even if not fed royal jelly doesn't seem like the kind of thing that would be hard to spontaneously happen.