The information based cheats are another story (insider trading, spam to raise stocks, ...). The issue is that it's very hard to prove so everyone (the rich) play.

An exchange is place where the one without information give plenty of money to the one with information, this is not going to change  :).

Other schemes you suggest seem to be based on the corrupt brokers / specialists operating in some US exchanges, and they no longer exist when you've removed the fat dinosaurs (they are disappearing slowly), in real electronic exchanges with no recurrent "upstairs" shadow deals.

Some electronic books are not fully open (hidden sizes, ...) but that's not a real issue.

Then the obvious question (related to your "open" and no one here yet) is why are we setting for continuous time trading from open to close?

In particular I like the way the day closing prices are fixed in some market: everyone has five minutes to put all their buy and sell orders in the book (with no execution), then the price is set to the level that maximise volume and all relevant trades are done at this level. Doing that something like four times a day would be largely enough. If there's a news too close to the five minute, the exchange can delay by 30 minutes or one hour and that's it.