Let's keep it basic. Can you show me (in the law), where market makers are required by law to tighten bid/ask on an exchange?? You can place your bid/ask on the exchange. I can see it and respond. I know at Fidelity (options) I can request which exchange be used when I trade. Joe Schmo can see my bid/ask also and respond. If your broker forces you to use PFOF, go to another broker. You get what you pay for. It is hard to have your cake and eat it too...
Just read the rule book, it's all easily accessible published info; https://cdn.cboe.com/resources/regulation/rule_book/C1_Exchange_Rule_Book.pdf