Steve Foley writes:

This knowledge is required for a private pilot in the USA. I suspect it's
similar for other countries as well.

It may be required to pass a test. But pilots aren't tested every day.

Someone who doesn't know this either is
not a pilot, or somehow has beaten the system. In either case he/she should
not be flying.

There are many people with drivers licenses who shouldn't be driving, and yet,
there they are.