It’s hard to teach kids “how to use the money”.
It seems that the contraindication of “money is unclean” certainly existed in ordinary Japanese families until the 1950s. My father and mother often scolded me, “Don’t touch money because it’s dirty!”
Even now, in Japan, except when purchasing goods, when you give cash to a person, always put it in an envelope and don’t give it away. When there is no envelope at hand, they all have the etiquette to say ”I’m sorry to give it to you without an envelope”.
When dealing with money, we must have a quarantine system so that it is not contaminated by the unclean pollution it secretes. This is a rule since money was introduced into human society, but until the 1950s, it was common sense in Japanese homes that “do not talk about money in front of children” “Talking about money in public” was a contraindication that you could get punched by your parents.
I encountered several people who left the store saying “Oh, I paid here” when he paid for a bill after having a meal with some people. I thought “Wow, he’s an adult,” but I thought he was an “adult” not because he paid for everyone but because I was impressed by his skill that he did not show him putting his money in and out.
Not showing money to others when you use it for them. It seems that it was an adult condition about the handling of money. In that respect, the money story seems to be close to sex. Both are only allowed to be accessed by “adults”. Both must be proficient in how to handle them neatly, but do not show others what they are dealing with. Children have no such skill. Therefore, it seems that it was common sense until the early modern era that children did not touch money and sex.
It was no longer common sense somewhere.
Impure isn’t the same thing as getting sick. Children who have been exposed to money or sex as a child will probably be prevented from maturing. I think that the children were regarded as “foulness” by annihilating the thrust that led to maturity