I know very well. But that new hire somehow managed to find that time, didn't they? If they are that much better than the long term folks, than the salary parity seems to be justified by that also.
It's easier to find the time if you're already laid off / between jobs, or your current position is awful for whatever reason. Otherwise, for most folks with tolerable jobs and things to keep them busy outside of work, it's tough to justify the time (especially since it often entails taking time off work).
The effort to search, even in good times, shouldn't be underestimated
The measure differs by the person, but I've legitimately been putting up with a job bad for my mental health for years. We can get accustomed to a lot
This only happened to get better for me in the last week because an opportunity landed in my lap. Had my network forgotten me, I would toil here for years until something broke permanently
I don't think the salary difference is completely unjustified. It makes sense companies want to save as much as possible. Constantly being on a job search is not feasible though, at least not if you want to have some time for yourself and family.
There is a sort of asymmetry with how full time salary jobs work, where companies push employees to their limit, implicitly asking for all their focus (or else you risk bad reviews or worse), and at the same time they treat them like assets than can be moved around like chess pieces. The consistent thing would be to allow employees to do their job without caring about the organization, without liking the product, etc., or if the company wants that level of loyalty and passion, they should reciprocate and make sure their salary is growing with their careers and compensating for things like inflation.