1) Job posting fraud isn't as much about quantity (like email spam), but the quality. Idk if some minor sats barrier would prevent it.

Ongoing payment requirements are a good proxy of the job ad still being active, but a weak prevention of scams.

2) the "trust issue" is one of the main problems in the recruiting space. Neither side of the negotiations can count on sincerity of the other side. I think some sats escrow preventing ghosting could be a nice solution. Also, seeing how many other jobs/candidates is the counterparty actively engaging, and of course, reputations.

3) Search relevance would be an issue too, but solvable with a new event kind and client.

4) candidate management would also need to be solved, and automated. Anything with n+ candidates creates significant overhead for the recruiter.