The money is sent as a donation, because otherwise we would lose a big chunk of the money as PayPal commission. We also don’t want to risk a charge-back.
Also note that PayPal might try to scam you into doing a useless currency exchange. For example, if you’re paying with USD, they might propose exchanging to GPB or EUR for an extra fee; make sure you do not allow it. They might even do it two times (an additional time at the final confirmation), therefore pay attention.