There are GoFundraise sites (if not GoFundraise itself) that are doing exactly this - but I'm sure they aren't the only one.
Perhaps their aim is easier future (one-off) transactions for the customer, but when transactions presented as one-off on the GoFundraise site are actually prompting for a recurring payment authorisation in the paypal portal, there's some misleading stuff going on. To quote the actual Paypal payment portal for a one-off ticket purchase from GoFundraise:
I want to use my (payment method) for my automatic payments to
GfPayment. Payments will be made first from my PayPal balance, and
then my chosen payment method above. I understand that if my payment
method is unavailable, PayPal will charge my backup payment method and
my bank may charge a dishonour fee."
Pretty suck if you start copping fees because of recurring payments you didn't intend on authorising. My preferred solution is:
A PayPol checkbox saying "one transactionn only" that appears when vendors request recurring approval would fix the problem, for all vendors.
(The alternate approach of getting developers to amend the vendor site would be an uphill battle, and only fixes the problem for a single vendor at a time).