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by kube-system 841 days ago
These are not authentication mechanisms, they are error detection mechanisms. This article (and these error checking algorithms) predate the time in which anyone could just throw data at a centralized API to see if you can get a 404 or 401 in response. A lot of the systems that used these numbers in the 20th century were offline and/or slow to process. e.g. the Luhn algorithm which credit cards use was invented in 1954.

Also EANs/ISBNs don't have other authentication factors available. You don't want a mis-scan for product A to accidentally charge a customer for product B. You want to detect the mistake.