I'd love to figure out how to quantify this.
What you say must be correct some degree, but to what extent?
I seriously wonder what percentage of US households in say, 1975, did not receive any newspaper subscription for example, what's the dataset you look at for that?
Or even adult literacy in the United States. You could apply this same thinking to many non US parts of the world, but lets confine it to the US.
I feel like it's stating the obvious that most major newspapers and media in 1975 did not reflect the true opinions of a blue collar, rural family in most parts of the United States.
Setting bigotry aside, popular support for isolationism and far too many other issues ran extremely deep.
My feeling is that generally speaking society as of 1975 was entirely predicated on a bottleneck of information flows. If your view was out of step with what the Ivy-League or flagship university educated editor was willing to publish, your views didn't make it into any form of mainstream media.
Nowadays, we directly have to confront those blue collar views, whatever their form.
I reckon that's probably good for humanity in the long term. 100-200 years from now addressing this information and political bottleneck will be good for society. But for now we are being directly exposed to the consequences.