Many websites, like e-commerce sites and social networking sites, use the HTTPS protocol to protect their users' sensitive data. If you have a HTTPS website you’ll be pleased with how easy it is to monetize using AdSense.
HTTPS should encrypt the data, not provide the data to an outside company with a mantra of "make a few more cents". Do you really want your customer, almost to-be, to be distracted with special interest ads from perhaps your competitors, just before they click "Complete Order"? Is there end to this?