This is true. However, they will not let you enter the details on the page itself.
In The Netherlands they are launching 'iDIN'. Which is a bit like OAuth 2.0, so it only provides the webshops with the things they need (and a bit more like age. So yay, privacy issues).
One of the problems is when this is done by companies instead of states. A company might remove your access for some, not obvious reasons. Just see current trending HN link http://www.dansdeals.com/archives/98444 where google suspended an account and with that the person could not use the google login anymore. Even for non-google pages. That is scary. A protocol like the EDUROAM system would be nice. In that case, credentials include a domain (usually a Uni name), and with that domain the home uni(bank) can be used as an authentication authority.
In The Netherlands they are launching 'iDIN'. Which is a bit like OAuth 2.0, so it only provides the webshops with the things they need (and a bit more like age. So yay, privacy issues).