Earlier quoted context omitted.
As always, who judges whether something is true?
The government, scientists, experts in various fields, people who have proven to tell the truth in the past, etc. You obviously still have your own ability to determine what fits your model of the universe and what doesn't. These are just groups of people more likely to have access to information that you might not. You don't have to trust anyone, but in a system where someone has to judge what is true, these groups…
But how has it been implemented in practice?
If you look at the raw numbers, generally we rely on the lowest bidders amongst Facebook/Google/Twitter's third-world-country subcontractors, as well as the Chinese government.