Not because they haven't been witnessed to but who is going to manufacture all the stuff for the survivors? Textiles and clothing, building materials, electrical components, air-conditioner for those living in the tropics and spacer heaters for those living in colder climes. Not to mention video equipment and computer tablets so that the survivors can watch the GB updates (though may they've gone to heaven but I'm sure there'll be plenty of the 'GB helpers', the next rank down, left).
The list goes on and surely the survivors won't be doing the same sort of manual labour that China seems to have the limitless capacity for.