Engineers that don’t test their own code have massively excessive confidence in both themselves and their QA team.

It’s okay, neither really has to test though. There is a group that will never fail to catch issues… They are inherently so skilled they need no training for such.

They are known as “former customers.”

But engineers do test their code for the most part. And some enjoy it. And QA teams also test. If you've got a product that makers it easier, do a 'Show HN'. Because I wasn't even one paragraph in before I scrolled down to confirm, "Yup, this is an ad."