I doubt that the median adult in any country would have a grasp of core concepts of physics, chemistry and biology. Yes, everyone hears about it in school, and then they forget; and that knowledge gets replaced by the pseudoscience babble oozing from mass media and from phonies selling things like homeopathy, creationism, antivaxx, chemtrail, astrology, aliens, conspiracies and such. Exposure to these undermines people’s ability to ground their world view in scientific principles.
You may remember your science education because you are in a stem field and your everyday way of thinking is grounded in science. But that doesn’t mean everyone else does too. Don’t fall into the “common knowledge is whatever I know“ fallacy.

I think this very much depends on your primary school teachers and parents. In the same way your parents can teach you literacy before school starts gives you an advantage, scientific literacy can be taught early and curiosity fostered or ignored or prevented. Without a good understanding on definitions you can get by with word usage but that's going to lead to many more misunderstandings or being more susceptible to misinformation. Like most of the people who object to evolution usually have a poor understanding on what it is.

Ask a bogan about the core principles and they won't even know what you're on about lol