It’s a good question, but one whose answer may place unnecessary blame on high school teachers. Teachers are charged with teaching high school kids math (and English) that is almost entirely directed towards the advanced academic demands of a university degree rather than the more practical needs the majority will actually use after graduation. Moreover, high school is simply NOT college in fundamental and foundational ways that impact the curriculum, even though the actual expectations and content treat it as such. I think we severely underestimate how profoundly the absence of choice for high school kids impacts nearly every single aspect of their experience there. The lack of preparation for college-level classes is just one (but a huge one for sure).