The point is there are a great deal of people, even in the US, who advocate that it is unreasonable to hold people fighting the west in general and US in particular to the Geneva conventions. I don't know where this idea comes from, because morally it is of course indefensible, but there you go.

I would expect the number to be bigger in Iran. I would expect the number among IRGC extremists to be even higher than in Iran in general.

Second: war crimes have 2 interpretations. First as violations of the Rome treaty which require that the state where the warcrimes happen has signed the Rome treaty. Iran hasn't.

The second interpretation of warcrimes is that they are violations of the Geneva conventions, and the reaction would be that the UN security council intervenes. Well, the UNSC has preemptively declared they will not hold Iran to account for warcrimes (to be exact: France, Russia and China have declared they will veto). So at minimum you can say that Iranian warcrimes will not have any "official" consequences.

The world and the UN have decided that warcrimes "don't count". As in there will not be any consequences unless the government of the country where they happened implements those consequences.

Third: Iran has already kidnapped a US civilian (a reporter, Shelly Kittleson) and are holding her hostage. This is already a violation of the Geneva convention. They have also kidnapped hundreds of foreign nationals of other nations and are also holding them for ransom, which is also a violation of human rights, ie. a warcrime.

So those are my three reasons Iran won't hold itself to human rights standards.