Because people (especially 20th century people) have been trained to ignore the evidence of their eyes and ears and trust only the word of the party.

Maybe this is anecdotal, but all the 20th century people in my life completely disregard what anyone younger has to say, preferring to believe that we're all entitled, whiny, complaining kids instead of realizing that we're adults in our 30/40s with genuine economic grievances. But they will blindly believe absolutely anything if it comes from personally preferred news media, even if its complete nonsense.

Gaslighting experts.