We learned how to make change because we played store as children with our little red cash register....c. 1950
Here’s my story from last weekend at a football game concession stand at my college alma mater. The order for three sandwiches and three coffees for my wife, my son and me came to an even $31. I handed the kid two twenties and a single - $41. He handed me back the single and wanted to give me a bunch of ones. I told him the change was just $10, give me two fives or a ten. He almost vapor-locked but recovered to get the change right.
Here’s the kicker: the stand was being run by the local high school band as a fund-raiser so the kid is no dummy. As I pointed out to my son, a band member through high school and college, the kid could be told that he was going to march 8 steps per 5 yards at 135 beats per minute and the music being played was in 6/8 time and he wouldn’t have a problem with doing any of that but math in his head just stumped him. It’s for the reason your illustration shows.
The thing about being confused about making change is true, but I have seen that with all ages. I often try to make my change come out to a round number and this sometimes confuses people. But I haven't noticed that this is happening more lately.
Saying what is the profit just by the sale of the wood is a bit misleading. You have the subtract out the price of the cost of cutting the wood like fuel for the truck, maintenance, etc., it could be asked: what is the cost of cutting down one tree. But that would be too hard for today’s brains of mush.