You should ask Boeing and Airbus about that. It's exactly what they do. They both spend mega-millions or even in excess of a billion creating a prototype and if it's liked, an airline company negotiates price and place an order with the winner and then mass production begins. That's creating a prototype AND it's the customer sitting back letting the company do the work at great expense, seeing what they came up with, and then deciding whether it's what they want before spending a dime. If not, they go to the competitor to place their order.

I also create websites for business, small cities, and industrial customers at one time. I typically had to come up with a foundational shell to show what it would look like to get approval and be paid before entering data, marketing text, e-mail addresses, etc. so the site was functional. If they didn't like it I had to make another one, edit that one, or not get the job. So that is also creating a prototype at my expense of time, getting approval and at least partial pay, then finishing it.

Let's see... even on a small scale I go to CVS to have photos printed, they do so, and then I get them from the clerk and review to see if they came out well. I can either refuse them, or buy all, or buy some, or wait for another set of better prints, depending on whether they meet my approval... thus I pay or don't pay after the work is done.