Isn’t he the same guy who’s been learning that more process is necessary to make cars safely and on-schedule? I’d be reluctant to draw any broad conclusion from one optimistic aphorism.
Eventually, maybe, a software process will be more like a manufacturing one but the variation in technologies, techniques and general fashion make that hard - even in limited areas such as CRUD web apps. I think you'd get the same outcomes with a manufacturing process as we currently get with software if every year you changed the engines, materials, electronics and transmissions.
Tester is for independent check you forgot about or did not knew about. Tester is so that you don't stop testing your code due to too much confidence.
Without testing, programmers tend to not have feedback on bugs, tend to think they don't have them and then tend to produce more bugs in the long term. Not because they are lazy or bad, but because they are normal humans.
Larger teams and process are really about scalability and robustness, because even high achievers have bad days, can only focus on one thing at a time, etc. If you’re running that lean you have limited capacity to handle anything unusual. It’s the same reason why the only way a 10x developer exists is if you compare them to a really unqualified, poorly managed group – almost nobody works on a single well-defined problem in isolation.