There's a better sense of safety if you do so from within, but we can't agree on what best standards are as an industry, let alone enforce them.

Actually it is necessary. That’s why your bridge engineer has to satisfy a licensing board that he or she knows what they’re doing before they seal a set of plans. Clients can’t distinguish good from bad engineering. They shouldn’t have to figure out if you know what you’re doing.

Actually it isn't necessary. Unlike bridges, very little software is safety critical. Clients don't need to try to distinguish good from bad software development, they can just require a certain level of performance and reliability in the contract with clear financial penalties for failure.