Not oversight nor historical: political.
Countries view ccTLDs as their sovereign property and territory on the Internet, and refuse to be (involuntarily) bound to any rules or requirements as a matter of sovereignty. It’s a huge source of geopolitical conflict within the IANA/ICANN split (and with DNS in general).
A number of countries have _voluntarily_ agreed to follow ICANN’s principles for good management and interoperability [1], but jurisdictions gonna jurisdict I guess.