I call bullshit on the headline. "PayPal handles 60% of web transactions" is not seen anywhere in the original source (which is about payment performance), and it is probably wrong.

NewRelic did collect data of their customers (and that is what they have said), but their customers do not include Amazon. You can not just take their data and claim they are 100% of web transactions (and NewRelic has not done that). I bet Amazon does make up a big percentage of all web transactions (though smaller than PayPal).