$15 per transaction is surely not bad, given much of their user base are probably Tai Tai's or day traders and those can add up quickly.
I've also wondered whether all passthrough fees are necessary every time? Any ideas? Obviously us users pay for every transaction - but if a Futu buyer matches a Futu seller, can they just do this internally as a nominee? Or are shareholder details actually disclosed with HKEX/listed companies and therefore every transaction gets officially lodged?