If anything they'd do the opposite so that the public doesn't get "the wrong idea" something dangerous is up. Just look at how Homeland Security made it illegal to measure how much radiation the post-9/11 security screening devices put out, forbade medical physicists from testing them, forbade employees working near the scanners from obtaining and wearing their own protection, and fired workers who wore their own dosimetry tags.

Unlike in medical facilities, the radiation comes from multiple directions. Also, the crew moves around the plane. The vests would have to cover an impractically large area.

Also, when radiation is blocked by matter, secondary radiation is generated. Since the composition of cosmic radiation is for sure different than the one found in other occupational settings, lead vests might or might not have the same effect. Also, the aluminium skin of the aircraft already has a similar effect. There might not be that much to be done practically.

It would be interesting though to let flight crew wear radiation badges.

Probably makes sense to add HDPE+boron radiation shielding to the entire cabin. Or the simpler one, just don't fly as high.