I am pretty sure, if smoking wasn't allowed for historic reasons, it would be impossible to sell tobacco as a new product. And as you said, some people are tolerated in the exclusion zones. As it is impossible to "see" radiation and few own decent measuring devices, it totally makes sense to me, that the authorities mark those zones. If this marking is done wrongly, one can criticize them for that, but there need to be some official guidelines. Especially seeing how bad people are about making judgements about smoking :).

But some of it is happening even here in Germany. Some of the Bavarian forests are still contaminated by the Chernobyl incident such that it is not completely safe to east mushrooms from them. Having a few dishes of those mushrooms per year is most likely safe, but the authorities are having warnings (but no bans) out. And the mushroom eating wild boars have to be checked for radiation before their meat can be eaten.