Tagging interface on Flickr still fails to prevent errors

On Flickr, the user interface for adding a tag to an image is just a simple text box:

As a result, people make spelling mistakes entering their tags and do not even realize it.  Consequently, for easy to miss-spell concepts, like Massachusetts, the photos are scattered over many miss-spellings of the tag:

Sure, we can blame the users for their spelling mistakes, but a better designed interface would have prevented users from making those errors.  Most other sites that use tagging, succeed at this.  Auto-complete is one mechanism that helps people spot and correct possible misspellings as they type, while still giving them freedom to type anything they want: