The fact is that kids should not be paid for chores on a chore-by-chore basis. This is perhaps the way that you should do things if you just need labor from your children, and want someone who will rake the leaves for cheaper than a hired gardener. But most parents also want to teach their children good values, and one of the most important social things to learn is about reciprocity in relationships. In transactional relationships, where you will perhaps never see the person again, reciprocity must be established immediately (paying for a cab ride, tipping a pizza delivery person). But in social relationships, immediate 1-for-1 reciprocity actually damages the relationship. If you were invited to a dinner party, would you try to pay the host for the cost of your food? Of course not. If it's casual friends, you might bring a bottle of wine, and if it's very close friends, you may not even do that, as you know you will be inviting them over at some point. Paying a child per chore teaches them to treat their family obligations as transactional obligations, rather than teaching them about the nature of reciprocity in a close personal relationship.
Also, when teaching kids about money, I think that many parents prefer to teach kids about "the value of a dollar" with cash, rather than with a bank balance. My parents opened a bank account for me in 4th grade, which was very unusual at the time, to encourage me to save my money, but even then I found that spending money was and is a lot easier when it's a number on a screen than when it's paper money that you take out of your wallet. By first finding pennies and nickels on the street, then getting $5 bills from their parents, and then graduating into a bank account, people learn to appreicate just how many found nickels it takes to buy a flatscreen TV.