Especially since these were put up in the 1980s.

If it were 20-30 years earlier, you'd write it off as Cold War/MAD Nuclear doomerism combined with that very particular breed of American fascism that inspired the Strangelove/Fallout aesthetic. People believing they could put the "best and brightest" down in bunkers to recreate an even better world after the inevitable collapse, without all those "undesirable" cultural elements polluting things.

But this was 1980. The Cold War was clearly ending. CFCs were still little-known as a global threat. The fossil fuel companies were still VERY effectively hiding the reality of climate change from the general public. The recession wasn't clearly visible yet. There was no reason to be a doomer. That was a great time to be an optimist.