Some really valid points there. I guess there would need to be a lot of reviews to be relevant for people in different regions. That would take time.
But then, some people travel a lot, and eat at good restaurants in different countries. Others just like to read about different food and see photos (though a lot of people just want information relevant to their everyday lives.). So I think you could write about your local restaurants and still appeal to folk who might live on another continent.
Also, you can choose not to upvote a fake-sounding review!
True, I travel a lot too, but still how would you know I was really there? Maybe a good thing they should add to save all of this from fake reviews is to do a selfie in front of the place or just to take picture of the receipt of the place, then you'll know it's legit and people are talking from experience.