But do require to be charged. I’ve had an unfortunate experience not too long ago where both my watch and phone failed to charge overnight on their usual cradle and come the morning were both as dead as the proverbial.
Now, my morning routine is very tightly timed and the gap between rolling out of bed and needing to be at the train station doesn’t allow for sitting around while things charge.
Luckily - my Oyster and cash cards don’t need anything fancy as electricity to work, so was able to get into work, but a coffee and blag a charger to carry on the rest of my day.
In summary - phones / watch’s etc… all very good and handy, but shouldn’t be your only means of accessing cash / services that are needed on a day to day basis.