I don't know where you heard this, but it isn't true.
Yeh, it is. But I'm interested - what conditions do you think drive the capture of sales data by GPA? What do you think they search for and where?
I'm interested in why you think GPA won't capture a sale if "CGC" isn't in the eBay title.
Have you seen eBay? There are hundreds of CGC books for sale right now that don't have "CGC" in their title, and orders of magnitude more in their completed listings. You think all these books aren't tracked by GPA? Their service would be worthless if this were true.
GPA has stated that they use a combination of different software tracking methods in conjunction with human ones. I'm guessing that they track images in addition to text, but that's just a guess on my part.
If your point is that they aren't infallible, and that some books may fall through the crack, then I agree. I think they stated that they capture 99.9% of all CGC books sold on eBay. So it's unlikely that a sale isn't captured, but not impossible.