Facebook payments do not require authentication?

Description

I recently paid a charitable donation from Facebook using PayPal as it showed up as a payment method. I was distressed when it did not ask for any sort of authentication from PayPal directly. How is that achieved? I removed PP as a payment method as I believe it is a terrible idea to link accounts in that manner. From what other services does PP allow non authenticated payments?
I am used to being taken to a PayPal webpage to complete a transaction and the fact that I was able to spend money directly from my bank account without ever logging into a site that I knew was tied to it is really scary. I can see FB wanting to make things as easy as possible but for PayPal to allow such transactions without authenticating is reckless IMO.
I am considering deleting my account on PayPal which is a shame as I am a PP user from way back before EBay even bought them. I have always trusted PayPal and to say I am disappointed is a gross understatement.
Muddy