It seems to me you keep mistaking reverb for autotune. There's a difference. Autotune is to be considered cheating while reverb is not. Reverb is just used as an effect to achieve a "fuller" sound. Autotune corrects singer's flat notes or wrong notes altogether, but usually creates an unnatural sound that most human voices wouldn't be able to produce. So it's fairly easy to tell whether someone relies on autotune and who does not. Implementing autotune in a live show would also be a great challenge. If singers really wanted to cheat it's easier to simply lipsync to a pre-recorded live track as Kiss seems to be doing for at least a few tracks nowadays. :)
Rob doesn't use autotune live. He's 71, he struggles to approximate some of the vocal lines and screams he was able to do 30-40 years ago, he reads most of the lyrics, sure, sure - but it's live and real. He - or the sound man, actually - uses the same effects most metal singers use, like reverb and delay and other "normal" processing. We just saw Iron Maiden a week ago, and even the mighty Bruce does that in places. One of Rob's favorite "effects" is just not singing choruses, letting the audience sing them, like on Electric Eye, Breaking the Law, etc 😄 Having said all that, there *are* prerecorded screams that play at the beginning of Judas Rising and Firepower but, AFAIK, Rob keeps his back to the audience when they do - so he's technically not miming to them.