I grew up in Massachusetts in the 90s and in my interpretation, finance was not taught in grade school (K-12) because school systems and teachers had a belief that learning about money would "defile" children and cause them to become money-grubbing greed mongers.
This is potentially a by-product of Puritan forms of thinking (the same thing that causes happy hour laws in MA to be draconian, and no liquor allowed to be sold on Sundays). I have no doubt early education is much more progressive now, but this is just how I experienced it.
I actually did have questions about money back then, but teachers would always shoot me down when I asked. It's possible this was because the teachers themselves didn't know the answers to my financial questions, making this a generational vicious cycle.