Finding an operating cashpoint late at night isn't especially easy either (and the reason most are shut down is that operational ones tend to attract muggings). It's a pretty practical system IME; having a payment method on you is no harder than having cash; indeed in this age of phone payment it's easier.

> You can still buy the oyster card with cash however, right?

You don't need to buy an Oyster card as contactless bank cards work on Oyster systems as well.

> Now try catching a bus late at night after the shops close - what a silly system.

London is a 24 hour city. :P