Why can't you overland in Iran today? Seems to be quite a popular tourist destination with many hardcore traveller types. I really wanted to visit when I was i

Why can't you overland in Iran today? Seems to be quite a popular tourist destination with many hardcore traveller types. I really wanted to visit when I was in the region but it ruins the US ESTA waiver for the rest of your life so puts some people in an annoying situation. Even worse is Iraq, which despite being a western ally sets off the same loss of waiver. At least Iran makes sense and can accept that.