The key issues are that the official app itself has gone down for whole days in recent years, phones aren't always 100% predictable, and while you may have made your own decision there is no paper option available for some Railcard types.So surely it is very simple if you choose to use your phone for your railcard then YOU take responsibility for that phone being charged. Both myself and wife manage to have our phone charged we have Senior railcards and my wife is not overly good with tech but has coped. We do only buy from the official railcard site.
As for doing away with railcards as some suggest, well that would mean we wouldn’t use the train. There are always seats available on trains we travel on so that income would disappear.