Bob, you're missing something. The example you give " someone...

Bob, you're missing something. The example you give " someone places an offer for 500 shares @1$13. Someone else then places a buy order for 1,200 shares" . You are assuming that there are two parties involved, and it is a real transaction. But neither the buy or sell ever appears on line. It's a simultaneous sell/buy by the same person. All we see is an update in the course of sales. Ever heard of a company called TIBCO ? They introduced Wall Street to simultaneous real time transactions back in 1992. Not the only player now of course. You still have no explanation for single digit trades... are they also arranged by this mysterious reload guy ?
The guys with the fat pipes, the high speed links to the ASX have a huge advantage over smaller players like us. Their trades take place in the background, whereas if I post an offer or buy order, it's all up there for all to see.