Likely because that generation was raised to believe everything they were told, starting from an early age with school, religion, then with television and newspapers, etc.
The younger generation were raised with media that spread obvious untruths such as conspiracy theories, pseudoscience, etc. and they learned to think more critically about what they are reading.
I'm probably over indexing on it, but the nocebo effect did not begin and end with a generation. People are remarkably influenced by what they are told. Even if they know it is unlikely or not true.
The younger generation were raised with media that spread obvious untruths such as conspiracy theories, pseudoscience, etc. and they learned to think more critically about what they are reading.