Hard disagree, it's very easy for a bot to use a credit card. And not only are card numbers often stolen, they're even given to teenagers these days, and can also be owned by businesses and exist entirely virtually... so I don't think you can assume the use of a credit card can always be tied to legitimate use by a single person.
Companies would offer all-you-can-DDoS plans at $20/bot per month if they could. Bots are only a problem to them because they prevent legitimate customers from handing over their credit card.
