You can purchase with a debit card to preserve your privacy if you'd like if your debit card is held by an institution that values that sort of thing. But the point of buying SIM cards with cash is to be sure nobody, not even Visa/Mastercard or your bank can tie it back to you. There's a difference between data privacy and having a phone number that isn't linked to your person (besides if someone manually reviews CCTV footage), the OP is advocating for the latter.