Gamma radiation not so much simply makes it through everything, but it does indeed take a lot of shielding to attenuate to save level if there is enough radiation to begin with.

The fact that it interacts with stuff is actually what makes it dangerous. If it went through every thing it would not interact with the worker either and would not pose a thread to them.

Btw. there is a type of radiation that is practically like that: neutrinos. Impossible to shield against, but also completely harmless if you are not standing right next to a super nova.