If we spent as much societal resources on elementary education as on healthcare, and schools had teams of intensively trained specialists come in and work with students 1:1 for many hours every week in the area of their expertise, then I would concede your point.
But a single conscientious and patient parent working 1:1 with a child consistently over the course of years is going to beat out a string of generalist teachers managing a 30-student classroom almost every time.
It takes a teacher/class months of overhead at the beginning of each year just to get to know all of the students and figure out what their skills and preparation are. It takes hours of overhead every day coordinating big groups of students, some of whom don’t want to be in a setting that inherently compromises their autonomy and often disrespects them, even in the best case where the teacher is kind and progressive. Feedback on student work is delayed and sometimes mediocre because carefully examining the work of 30 students takes a huge amount of time and effort. Glaring student misconceptions and gaps in basic knowledge and skills are allowed to persist for years. Generally little support is given to help students get over psychological blocks related to particular subjects or activities. Students are frequently cruel to each-other and teachers are often unaware or don’t have the available bandwidth to deal with it.
There is a categorical difference between lecturing to a class of 30 vs. direct tutorial, and the latter is generally much, much easier and more pleasant for both teacher and pupil.
