This is mostly due to the ionizing radiation argument. When it comes right down to it, it is the frequency of the radiation that is important. I think that people fail to realize that the only difference between a radio wave, light, x-ray and gama ray radiation is the frequency of the electro-magnetic radiation.
I don't think most people know why microwaves make things hot. If they did, I doubt they would be concerned about cancer.
It could well be so. That's their business. But we don't know what we don't know. So as far as I'm concerned, the jury is still out. The FDA WON'T SAY YEA OR NEA.