HTML Most browsers are fault tolerant, if they find code they do not understand they ignore it. This leads to untidy HTML which can lead to problems down the track, not only with text browsers but also with the newer versions of browsers which choose to more pedantic. To be available to the widest audience such issues should not arise on government sites. Not all browsers like frames, and frames don't always suit low resolution screens. If frames are used then a non frames alternative could be offered.
Frames block effective bookmarking.
If a whole web site is wrapped in a frame then pages within that site are difficult to bookmark, impossible without some technical knowledge. Even if a page is bookmarked, returning to that page will usually make it appear without frames, often making navigation within a site impossible. Contact Information A surprising number of web sites contain no contact details, physical, postal, phone and fax. Yet a significant number of visitors are looking for exactly that information. It should be available on or near the home page.