Why is air resistance neglected in High school physics?
Actually it is of use in practical life. In many situations, the air resistance is small enough to ignore. The fact that thousands of physics students can do actual experiments to measure g while ignoring air resistance is proof of this. It makes the equations a lot easier, but it also teaches an important philosophical principal in physics: the practical equations in physics are almost always an approximation, just good enough to get an answer to the accuracy you need. The rougher the approximation, the easier the equations are. Part of an education in physics involves learning when an equation is an approximation and when that approximation breaks down. As one basic example, we do a lot orbital calculations using one or more of the approximations that: (a) there are only two bodies, the earth and the satellite, (b) the earth is uniformly distributed in mass, (c) the earth is spherical, (d) there is no atmospheric drag. None of those is true, but it gives a decent starting point for c
