Zerodha Benefits from NSE Discounted Transaction Charges on Higher Turnover

As per my Understanding ,Exchange Transaction Charge are on Trading Member Level…I have not see any guideline which mentions exchange charges retail customer. Its not a Government Charge like STT, Stamp Duty.which are specifically charged to clients. Also, technically, NSE is also a Private Company…they fight tooth n nail…to not come under RTI…
Thereafter , brokers are free to pass on this charges to clients. …so…they may be charging as per lowest slab .