>Once you put it on finance, it's often cheaper than a monthly rail pass

Cannot this be said about anything? Choose a long enough finance and it's "cheap". Let's forget you'd be paying (at least in Europe) easily 1.6x the price of the car because of the small payments.

True, but it enables you to compare things against those which you can't buy upfront. London Travelcard zones 1-6 is £3264 annually or £313/month, but there's no option to buy multiple years in advance as if you were buying a car outright.

£313/mo is more expensive than the cheapest new car leases, but you wouldn't want to drive a car through London zone 1, and you'd have to pay £18/day in the congestion zone.