I don't understand the relevance of the town's history. Either the crossing is safe, or it isn't. The history may explain why it's unsafe, but it can never be a justification. That there's some reason behind the configuration is not something that must be pointed out - it's obvious that nobody chooses the locations of streets and schools by throwing darts at a panel. What the author is saying is that the situation is not acceptable - however it may have originated.

As for the 20mph speed limit - besides the fact that he specifically says they are irrelevant, since drivers don't respect them -, how would that have helped, considering it was 8:30pm when the accident happened? And I'm betting the "volunteer crossing guards" weren't around either. Apparently kids sometimes leave schools outside "schooltime" - who'd a thunk it.

Finally, if we're talking about what he left out - maybe you should add the other detail he didn't mention: that there had been already 15 accidents in the crosswalk in question in the last five years. So maybe it should have been clear by now that the methods weren't working.

(By the way, "the population exploded and the streets had to be expanded" is false. Governments have tools to control the growth of the population, like permits and zoning.)