They got it wrong simply because they either gave in to political pressure or made the most naïve assumption in the history of mankind, i.e. that non-vaccinated people are going to wear masks and not lie about their immunization status. And if this were a logical strategy, why did they keep the mask mandate in effect for health care settings and public transportation?
I would be careful saying it's only due to political pressure. It's effectively making the same argument the Trumpers were making in 2020, that the CDC and institutions are political actors and not following the best science.
Back then it was a plot against Trump reelection, and China something something, socialism, blah blah.
Is the left is going to be the party of science, then we should listen to the science and scientists.
I think they are taking a risk based approach. Goal is not zero transmission. The goal was to "flatten" the curve, not eliminate it. That's the trend you tend to see between states, but the area under the curve is similar.
I think they are well aware of human nature and impact of their recommendations, and didn't do this thoughtlessly.
Risk based also means we can limit masking to the high risk areas. Crowded transportation (buses, subways, trains) with poor opportunity for other controls. Medical settings where by nature very close contact with often ill patients/unknown samples is commonplace. Also add in LTC facilities.
Costco is not high risk. Risk profile is already low, and masks offer little additive value based on current conditions.
If you think this is wrong, what is your prediction that will happen? Are we going to see overflowing morgues over the summer? What is the science that CDC missed? When will demasking be safe? What's your metric?