From a high-level: the Iranian state hasn’t apologised for the 1970s US/Iran hostage crisis, nor its stated anti-Israeli position (see also: AIPAC lobbying), but most ostensibly because the IRGC continues to fund terrorism around the world - especially against US, European, Israeli, and Saudi interests.
SA escapes criticism because ostensibly they’re an ally(TM) of Israel and the US - and SA hasn’t committed state-sponsored acts of terrorism against western interests (9/11 wasn’t backed by the Saudi state - just by non-executive members of the extended royal family) and the economic and geopolitical leverage they get by being hosts of large numbers of US bases and getting OPEC to agree to use the Petrodollar which cemented the US at the centre of the world’s economy.