Is it possible that the cost of moving (both for techies and for mercenaries) helps create a signalling equilibrium?
https://en.wikipedia.org/wiki/Signalling_(economics)#Job-mar...
In the context of getting a degree: 'Spence discovered that even if education did not contribute anything to an employee's productivity, it could still have value to both the employer and employee. If the appropriate cost/benefit structure exists (or is created), "good" employees will buy more education in order to signal their higher productivity.'
E.g. if communication costs were really zero, then everyone would try to get a job by applying, which lowers the average applicant quality.
But if the cost of applying is high, then only highly committed, self-selected applicants who think they will eventually get the job will apply.