If this family didn't know the terrain, they might, like me - an outsider who doesn't know Oregon - look at a map and say, hey, let's take these smaller roads. It's a shorter route and it's getting late.
Of course, the route I mentioned might be completely closed. I don't know. Just throwing something out there for consideration.
There are towns and streets around here (Bay Area) that I would avoid (for various reasons: traffic, dangerousness - either terrain or human) just from living here that a person living elsewhere would choose just from looking at a map.
I'm assuming they didn't know the terrain, which may not be true.
http://fortetwo.net/OR.html
I agree with you and truly hope they asked a local rather than going by a map.