As the saying goes - "if it's free, you are the product". Especially in trading.
If the broker / bank is getting charged by the exchange for executing your orders (aggressive orders in the US), then one way or another it will be charged on you (+broker's cut).
Maybe JPmorgan has some way of doing just that without breaking regulations.
If I'm a retail investor and I'm buying large-cap US stocks, window trading my 50 lot of AAPL at 11 AM for free when the market is $0.01 wide is significantly better than buying $5 commissions. If I have 10,000 shares to buy in a small cap company, these types of systems will usually dump the order off into the market since the system will have few crossing orders. This likely will be a lot more expensive than $5.