I don’t think by default to check if a site is a verified publisher, but you have thousands of them. In order for me to find it, I have to actively think to look in the extension popup. This greatly reduces the likelihood that I will think to tip. I found out today that some of the sites that I love are verified publishers, and therefore I sent my first tip today.
Feature request: an Icon or something that shows up when I am visiting a site. Don’t wait for them to install a banner, just by default show the user something so they know they can tip.