Chart, page-7863

I still don't understand how these open and close bidding work. During those times, somebody would place a bid at several price steps higher than current ask, why would anybody do that when they could just buy at cheaper price at the current ask which can easily absorb their order? Same thing with sell orders, why somebody would place sell order several price steps below current bid? This is not unique with FLC by the way, happens all the time with different stocks during open/close bidding. I once place a sell order for another stock during pre-close, but somehow got executed at higher price, which is great but have no idea how that came about!