because when we say 'Geometry' in normal school terms we are referring to Geometry as studied by Euclid's book from ancient Greece, which was based on 5 axioms. it is also sometimes called 'straight edge and compass' geometry. And it was precise by it's design.
The trick is with Euclid's geometry that you are not just studying shapes and lines, you are studying how logic and reason works. It shows how far you can go and what you can accomplish by starting with very good basic assumptions about something, and working out the conclusions based on logic and reason. Philosophy and Geometry used to be very closely related subjects in schools of ancient times.
That is why we still study it even though non-Euclidean geometry has existed for 100 years and numerical approximation is much more important in the modern computerized world. In real life, engineers use computers to calculate tolerances within a precision, objects are never perfectly shaped. And in physics, Einstein's Field Equations are the most accurate known representation of the motion of bodies in the cosmos, and they are not precise in the sense that everything has to be approximated by calculation. There are no orbits that are perfect circles or ellipses, everything is approximated numerically in a computer. But we still study Euclid, kind of like why we still learn the alphabet, study Chess or Go, or still play cards or sports.