I think that your potential liability is no lottery - you know exactly what you are allowed for free and what you might have to pay for, and the charge rates are easily ascertained in advance.
The real lottery is in enforcement. You just don't know until you turn up at the airport whether or not you might be asked to pay anything, and if so for how much (with 45 kg on a 23 kg allowance they might only ask for payment for 10 kg, for example). I have got away with absolute murder on two separate and memorable occasions (55 kg+ on 20 kg allowance), but I like to think that that was the airline's generosity to make up for the many times that I don't have any checked baggage at all. (I know it's a lottery because mere politeness and charm got me out of one of them.)