This is another area rip for disruption. Does anyone knows why all these firms such as Fidelity get away with charging dollars on every trade? Is it because exc

This is another area rip for disruption. Does anyone knows why all these firms such as Fidelity get away with charging dollars on every trade? Is it because exchanges charge these feeds? But then I guess HFT people must be enjoying per trade fees of almost zero. Why they don't have to worry about per trade fees? To me it looked like each trade is an electronic entry in market and should cost near-zero dollars givens the volume of all trades.