Not really that silly. For example, IPv4 address space was initially mostly partitioned in huge blocks to couple institutions and companies without regard for t

Not really that silly. For example, IPv4 address space was initially mostly partitioned in huge blocks to couple institutions and companies without regard for the future. The difference is that Credit Card numbers are much easier to manage. The routing tables for Credit Cards are distributed by Visa/Mastercard to acquirers in the form of BIN files and it is extremely easy to add arbitrary mapping. So if someone gets an unnecessarily large prefix like "1" then the next day you can change it easily to ten prefixes "10", "11", "12" and so on and have a different organization for each.