You would be able to do this for a short while but unless you can make an agent that’s indistinguishable from you or you already have very bot-like traffic, they’d catch up pretty quickly. They aren’t going to just let a trillion dollar industry die out because some bots are generating traffic.
Scratchcards are sold at ecommerce sites which makes them significantly more accessible. If you really want to be “anonymous” (with very big quotes) you can buy gift cards for those sites with cash then order to a collection point. Otherwise, sure, it’s not as good as paying with cash but all there’s a trail for is that you bought Mullvad credits that cannot be tied to any account.