[jdtang13]

In all my years of using Google Maps, I have never seen any message like "we cannot recommend a route for the destination you have selected". Considering that human lives are at stake, the product owners should be more generous to acknowledge their lack of knowledge rather than cobbling together a route using outdated information.

It is completely conceivable for an app to say: "we don't know, please use a different app" -- it's just pure greed for user engagement that prevents owners from doing this.

Similar life-and-death situations have happened in the past with Google Maps users in Middle East.

[s0rce]

There are lots of obvious and not so obvious places where routes can't be calculated, for example, when asking for driving directions across the Darien Gap: "Sorry, we could not calculate driving directions from "San Francisco, California" to "Bogota, Colombia"" Although in theory you may be able to make it across by motorcycle overland, there aren't any roads and as such google maps doesn't plot a route through there.

[kzrdude]

Kind of insane that there's still a gap there.

[IfOnlyYouKnew]

I’ve seen various warnings on walking or biking directions, as well as on driving directions using ferries or toll roads, or crossing borders.

So they are neither categorically opposed to warnings for any of the reasons you mention, nor are there technical difficulties. I guess the case of roads that are dangerous just happens to be extremely rare.