I’d guess, in this case, imagining a wrongfully imprisoned grandma is thought to be more immoral than “just” a 50 year old. It also causes readers to imagine their own grandma in the same situation, instead of a stranger.

I thought Station Eleven was pretty good about it, small vehicles / motorcycles for a while, then bicycles and horses + wagons, plus a lot of walking. That was a wildly different scenario though (99.9% of the population poofed in a few day period), so there were a ton of abandoned resources for any survivors.