I agree, but I do know why it isn't mandatory in the US: It would be against the constitution because it would restrict the right to bare arms and would disproportionately impact second amendment rights of lower income Americans.
Nothing now, but you're the one talking about making something mandatory, which would be the government forcing us to do it. And again, it would not be covered in schools, certainly not all schools. People would have to pay for it themselves.
And anything deemed remotely non-essential is constantly at risk of being cut. I don't know how old you are, but I'm old enough to know that classes which were required for me (woodshop, home ec, typing, music) are largely no longer required, or even available, in most places.