The truth barely matters anymore. People believe whatever they want to believe, or whatever they are told to believe. You can be sure that Iranians are being blasted with propaganda just the same as Americans are being blasted with propaganda, except that currently Iran is cut off from the internet so the effect is much stronger.
You can't say for sure that you wouldn't wilfully join up if you were in that kind of information environment.
Information does go around even without the internet - doubt that iranians do not know about the things their government is doing in those mass executions.