Of course she and Charles may have had temple recommends, and Charles especially really seemed to have been genuinely devout, but the point was less about being qualified to go vs. actually going everyday. Without getting too specific, one just doesn't "go" to the temple, like to sit alone randomly or something. There is very specific work to be done and things are well directed/supervised by people who work in the temples. Here is some information, in addition to what others have shared.
Purpose of Temple and Family History Work