Scientists have to list all the sources they use. And they quickly get called out for doing mistakes in that regard and suffer a loss of trust in their work....
There is still an issue of human bias, though. A thought is not accepted unless it's widely accepted. Even much of our established science was once a pipe dream, even with reproducible proof, until it was accepted on a wider scale.
It's not as simple as just providing proof and letting people accept it, you have to appeal to them. Which is exactly what politicians do.
What would happen if politicians hat to work like scientists?
Scientists have to list all the sources they use. And they quickly get called out for doing mistakes in that regard and suffer a loss of trust in their work....