[nh2]

Because people don't know.

That includes users of low-level languages. They assume free() means free when it doesn't.

And assumption- and hope-driven development are less bothersome to the mind!

It's annoying to have to fact-check every sane assumption, but unfortunately it's required. Of course for anything that exists, somebody somewhere built a cache around it for average-case performance gains that destroys simplicity and adds pathological edge cases.

Most people learn this only when they try to run a real-world system that inexplicably runs out of RAM, or if they see unreasonably large number and actually start digging instead of just accepting it.