This from micechat.com from a poster. It does make sense.
Hi guys,
I'm a former Mark VI railie, and I stay in touch with a fair number of folks in the department. Here's what I've heard. I'm going to stress that it's what I've heard, and I can't represent this as absolute fact. Take that for what it's worth.
The short, short version is that Monorail Central cleared Monorail Pink in reverse into the Concourse (the Epcot side of the TTC) station without being aware that Monorail Purple was still in the station. Pink was cleared with MAPO override, meaning that the driver would have disabled the anti-collision system (there are a variety of legitimate reasons for doing this), and would have been acting on faith that Central wouldn't have cleared him into a dangerous situation because it sometimes is difficult to see everything you'd want to in the cab mirrors, particularly at night on a curve such as the one he was backing along. For whatever reason, Purple just sat in the station without attempting to avoid the accident, and was struck by Pink moving at the full 15 mph allowed during MAPO override. From what I understand, the driver of Purple was a new transfer from another department. Why Central would not have made sure the station was clear before moving any trains is a bit of a mystery, but I've heard that no one was actually in the control console (the control tower-looking place at Concourse) at the time. To my knowledge, there were no electrical or mechanical problems in play here. Again, I have to stress that I'm relating what I've heard, and I was not there. This is a second-hand account from others more familiar with the situation.
Okay, speculation time.
Why would Purple have just sat in the station and let himself get hit? Well, it was a new driver from what I understand, and when Pink got close enough to trigger Purple's MAPO system, it's quite possible that the driver of Purple freaked a little bit (any time a driver gets an unexpected red MAPO light, it gets their attention), and was so intent on looking at his console trying to figure out what was going on that he simply did not see Pink barreling down on him. I suppose it's also possible that the Concourse station didn't have power at the time, preventing Purple from leaving, but I rather doubt that was the case.
Why would Central clear a train into an occupied station? Inattention, most likely. As I said, I'd heard that Central was not at the console at the time of the accident. IMO, if this is the case, it's the root cause of the accident and whoever was Central should be strung up.