I don’t always, but I’ve never had the luxury of working on a greenfield project. With legacy code it’s a mammoth task to pull apart the spaghetti (more like a drawer of tangled headphones) to get the ideal test.

A better way of stating it, "It goes to show how few folks truly value testing in isolation" that is, having good tests in isolation is seen as a nice ideal to pursue, but delivering working code first trumps all.

"How do you know it works?" is a common reply to this line of reasoning, obviously we all have an idea of what "working" looks like, it's just whether or not we have gone the extra step of formalizing it in the form of tests.

Could you elaborate on what you mean with this? It seems like you are hinting at something which I apparently did not pick up.

Testing components in isolation is useful to ensure that your components work as expected. But it will never ensure that your whole system works as expected, unless the interaction between your components is so simple as to be obviously correct (which, in my experience, is almost never the case).