Wow! There are a number of articles linked in that long chain of comments that expand upon the issues talked about:

https://underunderstood.com/podcast/episode/yelp-grubhub-dar...

https://www.vice.com/en_us/article/wjwebw/yelp-is-sneakily-r...

https://www.inquirer.com/food/grubhub-doordash-caviar-restau...

These are some slimy business practices. A number of these stories also sound grossly illegal.