Most "international" standards are international only because the corresponding standard organization is ultimately operated by multiple nation-states. In reality the organization just appoints some experts to write the standard and brand it with their blessing, so the standardization process is hardly international. For language standards, those experts typically include original designers and whoever wanted to standardize the language. (Otherwise why would anyone want to join this tedious process?) A diverse group of experts is very rare for such standards.

It is another myth or fetishism that international standards have some inherent mechanism to ensure the compatibility. Such quality can be only maintained when standard editors take care of that and there is a comparable industry support. Missing any one, the compatibility can be easily broken, and conversely any specification---formally written or not---can maintain the compatability when both are satisfied.

The Rust Project also has international representatives vetting new additions and ensuring backwards compatibility.

Are those standards really useful though? I'm under the impression that Perl/Ruby/Python/etc. have done well enough without.

Hilariously, Ruby actually has an ISO standard, and it is absolutely useless.

It has been fast-tracked from the Japanese standard JIS X 3017, and I think there was a strong incentive to standardize due to Ruby being the only current mainstream language originated from Japan. (I recall even the Ruby Association [1] is supported by Matsue, where Matz was born.)

[1] https://www.ruby.or.jp/en/