The exchange you are referring to is IEX [1]. Michael Lewis (author of The Big Short) wrote Flash Boys about the intricacies of low latency trading and this exchange [2]. One of the primary "unfair" aspect of HFT is Front Running and has been illegal even before electronic trading (the name comes from traders racing ahead of big buyers in the trading pit). It was a big problem during the advent of electronic trading but has since been tamed. Exchanges arbitraging off their clients order books is another matter. Trading fast in reaction to real time (public) events is a market efficiency. Not accessible to the masses, but neither was traveling to wall street to place a trade.
[1] https://en.m.wikipedia.org/wiki/IEX
[2] https://en.m.wikipedia.org/wiki/Flash_Boys