Maybe, as opposed the various theories on what happened, involving somehow "low" employee pay, or possibly due to the lack of and/or failure of PTC, which is fairly speculative blathering, there is a more rationale explanation...?

Just maybe, the laws of physics might offer a simpler and less convoluted set of theories for an explanation, like the one about how bodies in motion, tend to stay in motion, especially when trying to stop on icy tracks?

This was one of the things we saw on the cool Russian video of really cool trolley crashes.... the one that went through the intersection, and into the truck, coming down hill on ice.

Neither a lack of PTC (they actually do appear to have a similar internal LRT control system) nor low wages would have anything to do with that.

There will be an investigation, and a report, then we will ultimately learn what happened, including any weather related, track condition, control, and/or human failures that may have contributed to it.