Compostable bags?

We do quite a bit of composting here at the homestead.  Probably somewhere in the range of 100-200lbs of vegetables, lawn waste, and other stuff each year.  I thought it was interesting when Sun Chips came out with fully compostable bags a couple of years ago. (Strangely, they stopped selling them because people thought the bags were too noisy?!)  There were even pictures on the back showing different stages of a bag decomposing over 12 weeks.  After eating a bag of chips, I put a bag in a compost pile (this was 2 years ago).  This wasn't at home, it was at a cottage in the Adirondacks.  I was back there again last week and decided to check on the bag.  Here it is.  It doesn't look like there has been any decomposition at all in the last 2 years!  It was partially buried under a bunch of other stuff, so it had plenty of contact with the soil/compost.  False advertising!!