I've got no idea why you're being downvoted - perhaps your last paragraph is a little harsh. But you're right, it's odd not to see mention of PayPal. It works, it's inexpensive, and for non-US businesses it's one of the few available options.
He's probably being downvoted by people who have extensive experience in dealing with PayPal. Dealing with PayPal's rather frequent API outages can be hell for businesses and developers. If you have a small enough business that you don't need to use the API, then go for it, but otherwise, you might just wind up scraping the PayPal site pages when there's an outage.
