Whether or not it's more often verified, it is definitely more verifiable.

One is a count that is likely in the millions or tens of millions of people and made up of nearly-anonymous people from around the world. The other is likely in the tens and made up of people in a single building.

A journalist could come to your office and make a pretty good guess at how many people work there. That's not to say people don't lie about it, but I think it's reasonable to expect an independent third party to be able to roughly figure out how many people work at a company even if the company wants to lie about it. I don't think it's reasonable to expect the same with web traffic.