Why Did Kellogg's Not Put Individual Cards in Cereal Boxes from 1981-1983?

Kellogg's card collectors certainly know the story about why the 1971s are more expensive.  The company didn't offer mail-in set's that year, so there are a lot less of those cards around.  That's disappointing because I hope to get a factory set from each year that Kellogg's produced a set.  

I'm also trying to collect each card in it's original unopened wrapper.  Kellogg's messed that up too since the 1981-1983 sets were not distributed in boxes of cereal.  One had to buy the entire set from the company through the mail.

Did Kellogg's issue any samples in 1981 of cards in the individual wrapper?  Has anyone seen one?