Before 1916, you did not touch the groceries.
You walked into a store, stood at a counter, and handed a list to a clerk. He went behind the counter and got your things. You never saw most of the products. You never compared anything. You certainly never wandered.
Prices were often not marked. The clerk knew them. Sometimes the clerk knew a different price for you than for the person before you.
Then a man in Memphis opened a store where the customer walked in, took a basket, and served themselves.
Everyone thought it was ridiculous. Customers would steal. Customers would not know what to buy. The clerk was the whole point of a store.
It was the single most consequential idea in the history of American retail, and you have been living inside it every day since.
The shopping cart. The price tag. The checkout line. The impulse purchase. The store layout designed to walk you past things you did not come for.