renaissance poisson

I don't think it's a ploy (although it might be); I think it's just shitty design that no one figured out how to fix. They wanted to make the buying process as painless as possible, so they slimmed the checkout process down to one button, but that design has no way to group multiple purchases, because all of the state vanishes once you hit "confirm". And they wanted the email to go out quickly, so there's no hook where they could wait 10 minutes or so and see if anything else has been bought.

I almost never get anything non-free (because that way lies another $5-10K a year in expenses), so they're not really getting me to do anything unwittingly.