We don't see everything the Queen does, either. Two days ago, I posted the number of engagements the Queen undertook last year. If I remember correctly, she undertook 325 in the U.K. (380 total, including Australia, I would suppose). But we didn't see her at every one of them. As a matter of fact, we saw only a small fraction of them. The same can be said of every member of the Royal Family. But we do believe they're working.
As for Diana, I don't remember seeing her daily or even all that often in her first year or two in the Royal Family.
Cindy