[sirn]

Fun anecdote: Thailand's entire banking network (including regular wire transfer) was implemented with ISO 8583 (!). Part of the AnyID master plan (later renamed to PromptPay) was to replace the country's (ab)usage of ISO 8583 with ISO 20022. The Ministry of Finance hired a UK-based Vocalink to build this converter, among with other systems MoF hired them for. (AFAIK, the entire stack was written in Erlang.)