When my car makes a noise, I take it to Don the Car Care Man because aside from replacing the battery and windshield wipers I can't do much. If they told me I needed to get part X replaced, I'd trust their input and buy part X.
When people visit eBay, there is an inherit level of trust placed in that site. It's a legitimate business used around the world. If a listing links outside of eBay and is asking for personal information, not everyone understands that such behavior is a sign of an attack.
My grandma doesn't know what a URL is. If I told her to visit my companies website, she would ask where it is in her bookmarks. Just like I would ask where part X in my car goes. To me that's a very basic question; to a car expert they might be thinking: "Good thing this guy is having us take care of the problem".