Most families I suspect don't know enough to do it or think of routers as set and forget (If they get it to work, then job accomplished). I bet if you took a poll of all households 1 mile around me in an urban area, A less than a few percent are checking their routers at all to make sure they are up-to-date and a lot of them likely don't remember how to since setting them up years ago. To be fair though... I would think most homes are using ISP provided routers which typically are updated by the ISP. ISPs... you are updating them quickly correct?
Router manufacturers targeting homes and small business which likely might not have the skills to secure them really need to step up and have secure by default settings and only allow disabling of updates with lots of warnings about results like this with pop ups. Security updates need to be provided for quite a long time too for that target market (8 to 10 years).