I know this is what parents should be doing, but unfortunately a lot are not teaching their kids these things. Some are and thankfully I have parents trying to prepare me with things like this. But I know plenty of people that are so clueless about being an adult. A lot do not know how to manage their money, they don't know how to do basic household chores, etc.
Home economics (may be called something else these days) and auto shop should cover most of that list. Then, of course, there's the Internet, which has information on just about anything you could possibly want to know, but is used to piss, whine, moan, and snivel about how no one teaches you anything. Balancing a check book is basic math. How do you idiots have such a hard time with it?
People really tried and still do, we are close to losing music and art as well in a lot of schools. We have to be willing to invest money in our school districts. Education is an investment, but many people don't see it that way.
In my school they only taught the special needs kids the "life skills"; the rest of us got math, science, english, and all the other bullshit classes that you "need" to get through life.. The only reason I needed most of that stuff was just to graduate high school.. lol
I've taught these and similar things to my kids, and tried to teach some of them to other kids that I interface with...like nieces, nephews, friends of my kids (one was over while I needed to change propane grill tanks, so I showed him along with my son). Some are open to learning new things, and some are not. If you attempt to broach the subject and get a big eye roll in return, after a while you lose the motivation to try to be a teacher. One kid wanted to get a job in order to get a phone, and I asked how she'd get to work; she said she'd buy a car. How much do fuel, insurance, maintenance and license cost? She didn't know and had no idea how to even figure it out or get a reasonable estimate. She was sure she knew everything, and any question I had about the reality of the situation was interpreted as just one more adult oppressing today's youth. So I let it go. I later found out she made a long series of bad (or at least short sighted) decisions, based on unrealistic expectations.
How does this have no "thumbs up?" It accurately answers the question posed of "Why didn't someone teach me these important life skills?" It turns out that when your dad or uncle or neighbor tried to do that, you were too busy or too tired or didn't feel like it or too engaged in sending memes to your friends about why nobody caused this knowledge to be transmitted into your head with no effort or time on your part.
Edit: In my rage, I didn't read the other comments first. :(