If you've got tests then you've already seen how many stupid mistakes you make, long before release. To get that far and still not have learnt enough humility to accept there may be more is quite the achievement!
Having said that, I still support the sentiment that most code is buggy. It's futile to expect pervasive perfection.
I was trying to give a reason why people, myself included, don't learn the humility you refer to.
Nice to know it's not endemic!