Brokers have an EOD brokerage deal. Essentially, they pay for...

Brokers have an EOD brokerage deal. Essentially, they pay for one set of brokerage (buy and sell), regardless of how many trades they make throughout the day. This is one of the reasons why HFT/algorithmic trading is possible.

I think of the ASX as a casino with 'smart money' being the house and 'retail' being the punters. HFT/algos are just one of the methods employed to stack the odds in favour of the house. As punters, we need to learn to count cards in order to keep our shirts.