Could it possibly be that most in-demand senior developers with the qualifications you posted are already employed and quite happy with their current jobs? Good companies would be looking to retain these people as best as possible and I would think it would be difficult to pry them away. This group is also full of entrepreneurial types that could be immersed in their own projects — why would they want to drop it and work for someone else?
Some other thoughts I had:
- “Competetive” pay would be a red flag if I saw that in a job posting. It signals to me the compensation is based on what other similar companies pay and not based on the value of the individual in question.
- From personal experience I don’t find that senior level developers need to pair program 100% of the time on all tasks. And even with all the tools available, remote pairing is still a pain.
- I wouldn’t say working with “cool” technologies would also be a selling point to experienced developers. One would probably prefer to work on interesting or challenging problems.