Supermarket cashier is not traditionally considered a career path by modern standards. It's a good first job for those just starting out, certainly great summer work for high schoolers, but not something you think of as a stopping point on the path to making an independent living.
Not such the case fifty years ago, when this training film, "Supermarket Cashiers: Ambassadors of Goodwill" was produced. A lot more went into the job, as you'll see. Barcodes had yet to become standard, so all goods' prices had to be manually punched in, along with the proper department each item came from. Errors were easier to make and were more costly. Coupons, checkwriting, price discrepancies -- all the things that take seconds to solve these days could take ages in some situations way back when.