Perhaps by paying one's ad is shown higher.

That might be the business modal here, but I doubt people browse job listings in the same way they browse other lists of data, so it's a bit silly. If you're looking for a new role once you've filtered a list of all jobs down to a list of of possible jobs then every result is equally important - people won't just apply to the first result as if it's the best one. They'll go down the list and apply to all the ones that sound good and match their criteria. Promoting a role to the top of the list will only mean people apply to it first. Who cares about that?

Recruiters...