Thats a simplistic view of restaurants. From a purely market perspective, people already do this with personal loans, credit card or otherwise. I do agree that evaluating the final software's value is difficult but for a loan lender, it's only a matter of credibility rather than success.

As long as market actors don't do anti-competitive practices, I still don't see why a successful software can't be replicated and you can't compete in the same market niche. The user interfaces are one area which can obviously be different. Enterprise software is full of replicas.