That was overly sarcastic for hn, but the point was that there is not a single human alive who can explain everything they do. At some point you are going to hit an assumption that you have not personally verified
E.g. if you claim that the NSA is listening into every single thing that is said on everybody's phones and watches, I would know that not to be true from bandwidth and battery arguments. Selectively, sure, but I could tell if it was happening 24/7 to my device in some sort of dragnet surveillance.
How did you verify your physics and engineering knowledge? Did you run hundreds of thousands of experiments to verify every single law and property of physics? At some point you are reaching a piece of data you learned from someone else and did not verify or that is an assumption because it's currently unknown how to explain or takes too much effort to verify while living your life.
On top of that, the OP was talking about how it was impossible to verify _everything_ in our lives nowadays. You mentioned nothing about biology or chemistry. How do you know your diet is the proper one? Are you sure about every chemical you interact with and how it affects you? Do you properly understand copyright and other IP law when you make a YouTube video using someone else's work? Did you get the right permits to put up that shed on your land that complies with the regulations from the 7 different layers of polity that cover you? Life is far too complicated to understand every facet and it only gets worse as we realize things are more complicated than we previously thought
That's extremely dangerous IMO. If you have a populace that is not literate or engaged, you end up with a slave society. Just see the rise of the concept of a "thought leader" [1]. It's quite scary when you see the implications such a concept will have for society.
[1] https://newrepublic.com/article/143004/rise-thought-leader-h...
An interesting concept to that effect is that of "epistemic learned helplessness"
http://squid314.livejournal.com/350090.html
Basically, if you're not an expert in some field, then for any given argument, arguments of either side can be made to sound equally convincing to you, so - unless you have time to become an expert in every domain you encounter - your best bet is to accept the general scientific consensus on the topic.
(If anything, Occam's Razor is very useful to determine who is arguing for the generic scientific consensus, and who is arguing out of political reasons, or fear driven by ignorance.)
Who is there that is telling the public what the science says and that the public can trust?
Government agencies and their scientists?
They often have a tendency to make recommendations based on weak science, and if they are regulating an industry with a lot of political influence they may even make recommendations that go against what the science says.
For an example take a look at dietary recommendations in the US. Almost everything that has gone into them has not held up. The public followed them, reduced fats, eggs, and protein, and loaded up on carbs...and became fat and diabetic.
How about non-government advocacy groups?
They botch it too. Continuing with the dietary recommendations example, the American Heart Association, for example, jumped on the unscientific "fat and cholesterol bad" bandwagon, and spent decades giving people harmful advice.
Industry scientists?
Their employers often get to decide what they publish, which means that although the industry scientists might not outright lie about results, they may remain silent about results that would go against their employer's interests.
Academic scientists?
This is probably your best bet. The problem here is that academic research is often not directly on point for the particular issue that regulators or legislators are addressing. Academic researchers are more likely to be doing the basic research that industry, government, and NGO researchers should be building upon.