The unfortunate part is, a lot of GA pilots are unaware of this.
Speaking for the US, I believe that one of two reasons are most like the cause for this lack of knowledge. With regards to the PP syllabus, there are many subtleties of aviation knowledge than cannot be taught within the limited timeframe of the PP instructional period. This is where getting out and flying a lot will expose what was not taught initially.
Secondly, I believe that (for good or bad) many flight instructors are the fast-track types - in other words, those who are screaming through the ratings to become a right-seater for the airlines, stopping at CFI or CFII only long enough to accumulate the hours needed to move on.
Therefore the reality is that these CFI/CFIIs many also not be as experienced in these subtleties and therefore do not pass them on. Of course, where one's flight school is based would make a difference, whether it be a busy class C or even class B airport (BWI comes to mind), or whether is it a small, single strip uncontrolled field 100s of miles from a class C or larger.