that does not say anything about proving who you are
Are you trying to make Pelosi's argument for her? No, the Constitution doesn't mandate photo identification to cast a ballot -- this was deemed necessary due to all the voter fraud going on this country. Identifying yourself at the polling place is a method to ensure that people do not/cannot cast multiple ballots, and it's not enough to simply have the gal behind the table attempt to compare signatures in the book and on your ballot.