Aldi Süd cashiers learned the prices. They actually choose prices that were easier to type and as few different prices as possible. Barcode scanners were installed in 2000 in anticipation of the Euro introduction.

Aldi Nord cashiers learned three digit codes (around 800 ones). Scanners were only introduced in 2003 because they started to sell loose produce which is weighted at the checkout. Additionally, that allowed them to get away with less training.

The checkout speed dramatically decreased since then. Before they had to pick up each and every item they often entered the numbers faster than you could load the items onto the checkout line.

6000 items per hour was the target before. Now it's around half which would have gotten you fired back in the days.