BillGuard indeed has only access to data in a read-only fashion. Yodlee does have a mix of web scrappers as well as data feeds for certain financial institutions. They power different features for banks such as bill payment and others but companies like BillGuard don't have access to these APIs.

On its end, Yodlee is heavily regulated. Like a bank and sometimes even more: http://www.yodlee.com/yodlee-security/