The stylised facts seem to be that historically, brokers would charge a commission, receive PFOF, and give a large chunk of that PFOF back to the customer in th

The stylised facts seem to be that historically, brokers would charge a commission, receive PFOF, and give a large chunk of that PFOF back to the customer in the form of a better price (smaller spread). Robinhood then did away with the commission, but pocketed the PFOF, offering consumers a worse price. Thus: retail consumers with very small orders would be better off at Robinhood, but with even orders of a few thousand dollars it would have been advantageous to go with a small fixed fee, but execute with a better price. (Note that all of the above is within the NBBO, but that is not a tight benchmark, apparently.)