Tap to Pay is certainly a gamechanger. Recently visited the UK, most places weren't accepting cash, and everyone insisted use Tap to Pay on your card, phone or watch on the sideways wifi symbol on the terminal. My dad misplaced his visa card, and almost lost it at a business. From that moment, I told him, give me your card, let's transfer it on to your watch... no more fumbling in your pockets. Done. A 75 year old found a new skill, and ability to use the toilets in Hyde Park that were tap to use only, then the same routine in the London Underground.
Tap to travel on the London Underground really is amazing. You certainly miss it when you're in a city that doesn't have it.