I think a cost per application system makes much more sense in terms of measuring ROI and trying to solve for cost per hire.
The hard part of creating a matching algorithm for jobs is dealing with people who are looking to change careers. For example the plumber who has been reading up on algorithms and learning C++ in her spare time. Your algorithm would likely classify this person to a plumber career track based on her experience, but struggle to show this person jobs in programming. On the flip side of your marketplace, you would likely screen this persons application from ever going to this employer for just the same reason. The experience on their resume is irrelevant for a programming job. This in my experience is the crux of the job industry problem today.
The hard part of creating a matching algorithm for jobs is dealing with people who are looking to change careers. For example the plumber who has been reading up on algorithms and learning C++ in her spare time. Your algorithm would likely classify this person to a plumber career track based on her experience, but struggle to show this person jobs in programming. On the flip side of your marketplace, you would likely screen this persons application from ever going to this employer for just the same reason. The experience on their resume is irrelevant for a programming job. This in my experience is the crux of the job industry problem today.