You think trigonometry is taught in primary school?

You miss the point also: I was taught trig in high school, and I remember SOHCAHTOA, etc - but until I looked at lines drawn on a unit circle and worked put what secant, sine, tangent and their corresponding ratios meant I didn't really understand trig.

Many textbooks provide much the same structure as in universities. However, I have had a lot of success in attempting to read far above my level, and satisfying the dependencies that I need along the way.

From a third world perspective, it is taught in high school but I rarely know anyone who gets interested in it after graduating, much less retain the knowledge that they learned.