"The answer is to build a process that catches mistakes. I don't think software engineering has really caught up with mechanical engineering in terms of process."

I agree. I'm not sure it ever will. But comparing software to a car and the relationship between the buyer and seller is too simplified. Software have bugs. Many more bugs than cars. Because it's not tested properly. Which we don't do because no one would buy it at the price which comes from proper testing.

You can accept this and write your contract accordingly or you can sit down, muck and be disappointed when it fails.

I'm not saying it's right - it's just how things are.