You didn't add anything. They just hadn't finished telling you the price yet.

Each fee was small enough to feel trivial. All of them were hidden until you'd already entered your address and card details. By then, walking away feels like losing. That's the sunk cost fallacy, and drip pricing is designed to exploit it.

StubHub's own experiments showed that hiding fees this way increased revenue by 21% and made users 14% more likely to complete a purchase.