How come you think discrete math is too hard to teach? Calculus has definitely been useful to me for understanding how rates and totals relate to eachother, which shows up everywhere -- and also understanding volumes and shapes! It's also the basis of differential equations which underpin all physical processes

I strongly disagree that calculus isn't useful. Without calculus we would not have self-driving vehicles, autonomous robots, safe and stable aircraft, spacecraft, or many other modern technologies we enjoy today.