Many tourists already get intimidated by language barriers and inscrutable timetables and transit routes; add tariff complexity (and the chance of getting charged with fare evasion!), and many just end up taking a taxi.

With these stored-value systems, you pretty much don't have to ever worry about doing anything wrong as long as you properly tapped in (and have the necessary cash to top up the card at the exit turnstile if you ended up "overdrafting" your card).

Now the remaining complexity is learning about and getting the card in the first place, and Apple Wallet really does an amazing job there in Japan. Not even having to install an app or create any account is absolutely amazing.