Technically neither does the transaction data. I mean, there's no technical requirement that transaction data needs to be stored on a central Google server.
They could have made some arbitrary statement like "by using the camera app you give us access to all of the pictures you ever take, so that we can back them up for you."
Maybe I'm misunderstanding google wallet, but isn't this exactly the kind of data that you would expect for it to collect? I'm not too shocked when my credit card statement has a list of merchants, addresses and times of purchases, nor when amazon (and newegg, and paypal, and...) has a list of items and dates purchased, which in turn influence the items they recommend to me for future purposes.
On the other hand, if you don't feel comfortable with google being the clearinghouse for the information...super? Use something else (and spur competition!). The OP's statement seems as monumental as which brand of credit card company he uses (and somewhat willfully blind in light of the information they can and do collect...much more than appears on our credit card statements).
They could have made some arbitrary statement like "by using the camera app you give us access to all of the pictures you ever take, so that we can back them up for you."