You get what you pay for with brokers/execution....ever since the Walmart way made its way into retail traders minds...theres a million crappy order routing systems for cheap.
Its all about cost...putting in TT, PATS or whatever infrastructure costs huge in initial outlay and must also be planned for expansion quite aggressively, right now most of the cheap firms overload their servers with 3x as many users/traffic as they should normally.
Not a problem in the day to day grind....but when any heavier action goes down, every little trader logs in and opens his 20 charts, the whole system gets tagged and falls into the shitter.
While I respect the whole watch your costs issue, its also quite apparent that most traders cant trade and lose all their money.....if only some more time was invested in their learning and training, instead of gobbling back and forth on rates.
Retail traders could trade for free...and 90% of them would still be unprofitable.