I recount, too. Mistakes happen.
I know that this isn't representative of all younger people, but about 20 yrs ago, my family and I were at a fast food restaurant while traveling. The electronic cash registers were not working, so they were adding everything up on paper. The young man waiting on us added everything up in twos. Added the first two items, then items three and four, etc. After adding finally finishing the first pairs, he started in again, adding the sums of his first go-round in pairs. Repeated until he was down to a final two sums to get our total. He couldn't add a column of numbers.