You're wrong though, you wouldn't prefer to hire B. A will quote you $2000, $500 up-front maybe, and B will quote you $2000, $500 up-front maybe. When you realize B is talking about two hours of work, there is no way you will ever work with him. You will prefer to find some cheap shoddy solution you can supervise for two weeks. It's just how people operate.

There's pretty easy proof of this. You would spend weeks of time, $8000 in recruiting expenses, trying to get a web marketing manager who can increase your conversion rate.

But if there is a web site that you could allow to A/B test some change to your layout - that its operator somehow comes up with very quickly or even programmatically - you would not give them $5000 for a few minutes of work. It doesn't matter what the 'results' are, or if it's in escrow or tied to the results: you just wouldn't. You would prefer to spend weeks of time and double the money on a web marketer who doesn't work as well.

And for that reason, such sites just don't exist.

There is no place on the Internet you can pay someone $10K for 20 minutes of work, even if those 20 minutes are objectively quantifiably better than the results you would otherwise spend 6 months and $100K trying to achieve.

Human psychology just doesn't operate like that.