More than that, you misunderstand how advertisers prioritise their money. They pay for outcomes. If they notice that over the past couple of months they’ve been receiving mostly bot traffic, they stop advertising. Not everyone all at once, but enough that revenue begins to decline. An ad based business that cares about the long term will do it’s best to weed out the inauthentic engagement.
Yes, naive attempts at manipulation will be detected these days on big platforms. 5+ years ago such naive attempts were successful, though. A few years ago I made a proof of concept to show how easy it is to make new Reddit accounts and automate them, and had registered hundreds of accounts. Those logins still work even though Reddit has cracked down on naive automation attempts.
Today, that's why many firms buy real users' accounts. They'll hire people to manually login to the accounts and post. There's also the perpetual cat and mouse game between bot creators and platform owners, and the platform owners who benefit from the appearance of increased growth and engagement that's actually just bot activity.
How they verify those outcomes, however, gets interesting. See, for example, College Humour going under due to inflated engagement metrics fed to them by Facebook video.
No tax, no flying cars, eventually not even humans around - just AI-driven companies endlessly trading with each other, in a fully-automated, self-contained, circular economy, from which sentient beings were optimized away.
This is my actual hoped-for endgame for the ad based internet. At some point Twitter, FB, etc will be exclusively populated by bots that post ads, and bots that simulate engagement with those ads to drive up perceived value of advertising. They'll use AI to post comments that are really just ads or inflammatory keyword strings to drive further "engagement." The tech companies will rake in billions and billions of dollars in ad revenue, we'll tax all of it and use it to create flying cars, high speed rail, and an ad-free internet closed off to all non-humans. Occasionally a brave ML researcher may venture out into the "internet" to take field notes on the evolution of the adbot and spambot ecosystem.