Why Don't Parents Teach Their Children About Finances?

I've never understood why most parents don't teach their children about finances. Don't get me wrong, the simple lectures of not spending money can help, but why do parents not go farther than that?

For example, my parents didn't teach me about progressive tax brackets, deductions or credits. They explained a bit about collecting receipts for write-offs, or they gave me a simplistic idea about taxes (like how the government will take away 5% in taxes from a dollar leaving me with $0.95). It was all rudimentary, but they never expanded on that. They also didn't teach me about utilizing debt correctly or investing.

Is this a cultural taboo? Is it because they are also ignorant about taxes (even after all these years as adults when I was younger)? Maybe they were too tired after work and didn't want to explain complex finances to their child?

This got me wondering because I'm talking to a coworker of mine who is 16 and he has no clue about simple terms that I think SHOULD be taught by parents.