Even when salespeople don't have a better understanding of your tastes they're more likely to be persuasive and more likely to add the perceived value to it... a salesperson who admits to hating something she recommends is a more memorable and compelling call to action than an algorithm

I'm sure Amazon's algorithms often do have a better idea of what I'd enjoy than many of my friends, but friends' recommendations are still more likely to induce me to act than a personalised promo email.