I seem to remember that there was in the last couple of years a re-definition of the user categories to whom the non-display fees applied. Does anyone know what the current criteria are for various exchanges - NYSE and Nasdaq in particular, but OPRA and CME as well?
https://www.cmegroup.com/market-data/distributor/files/mdla-cme-schedule-5-apr-2020.pdf https://www.nyse.com/publicdocs/nyse/data/Policy-NonDisplay_PDP.pdf I'm happy to give you my take on this with a phone call.
Non-display fees are still applied on some of the user categories. You can check for yourself for whichever stock you want to know the non display fees.