I think the upfront + refund + commission structure balances the incentives. It's something that is missing with ISA structures, which unevenly optimizes the school incentive. An upfront cost is table stakes.

The trainer is incentivized to perform because the collected tuitions might only represent a fraction of what could be earned. The commission is where the profit is.

I would personally be super motivated to sign up, especially if the curriculum and employer partnerships were attractive.

I'm riffing but I know it's a super hard problem. I wonder if game theory could or has helped here.