This is a concept I often find myself trying to articulate in political discussions. You have a situation that everyone openly acknowledges, but it is so entrenched that people may paradoxically behave as though it were completely unimportant.
As a contrived example, for centuries the people of Helmetvania have all worn 6-foot-wide spherical helmets. There are lots of car accidents, neck problems are endemic, and people often complain about how silly it is to wear helmets. The hot topic in this year's election is whether non-helmet-wearing should be addressed by longer sentences, or better education on the importance of helmets.
It's somewhat related to the frog in slowly boiling water, or to not seeing the wood for the trees, but what I'm talking about is not a failure of perception; rather, it's a failure to take one's own perceptions seriously when they seem to be at odds with the world.
Are there good words, phrases or even extended references for this idea?