I was intrigued by the economical part of it, not exactly the design, it's not really a unique concept, I've seen quite a few of them lately.
This will allow users to bypass agencies, newspapers, and other middlemen to gain ad space that's 90% cheaper.
Just how will those ads be 10% cheaper? Let's be realistic here, nobody is earning 10% only of what the advertisers pay, otherwise, this whole industry would have been dead a long time. 50% might be doable for extreme examples but 10%? Not
buying 
this, especially since you're offering a little too many freebies, not sure if you're not making this to be more attractive then it would be economically viable.
Also this:
It will not be atypical for a Bitfari economy participant to open up his/her wallet, perform 15 minutes of work and receive enough compensation to pay for a car.
Ads would be cheaper as you said they will cover the same amount of people with 10% of the cost but at the same time watching 15 minutes of ads would cover a car lease? Hmmm!
Next:
A store owner might close the store and keep operating his/her screen to save money for a future business. As is stated in Bitfari’s code, businesses will receive:
1 million free ad showings in screens of their city/market. This incentive will half every four years.
Again, you're showing participants with freebies, 1 million free views, good! What happens when you have 1000 businesses signing up, you need 1 billion ad views that need to be viewed and you're delivering those for free so who's going to be paying for the above user's car when that much free stuff gets has to view in the first time?
Now, I want to address one thing about auditors
What are you going to do when auditors get together for reasons that are politically or socially motivated, you have seen how people react when boycotting products or other more recent cases harassing businesses. If 51% of the auditors in an area don't like a billboard because they consider it let's say racist although it is not who is going to keep such a mob in check?
There are hundreds of those events happening around about different things the Robinhood scandal, Yelp and the restaurants asking for vaccination proof, and many more. Those ratings were bombed by people who have little in common, might be thousands of miles apart, and other than one or two of these activism moves that act like your average user, not a bot. Wouldn't then the whole network turn into a propaganda machine?
And being totally decentralized, you shouldn't be able to stop it, unless...you centralize it!
