I like the business model, but what prevents someone from looking at a developer's solution and incorporating it without paying the developer? Say the company is charged when they use the patching mechanism to bring developer's work into their product. What would stop them from simply going around this mechanism and just copy and paste the solution into their own repository?

Also is the developer responsible for fixing bugs in their solution? Can a developer exploit the process by submitting buggy code they'll be paid extra to fix? Can a developer be required to fix bugs in their solution?

If a company can't inspect code before they pay they can't be certain it's relatively bug free, if they can inspect the code they could use it without paying for it easily.