"Compostable" Sun Chips Bags

I've had 3 different Sun Chips bags in my compost pile for at least 8 weeks. They are showing no sign of decay. It's been pretty hot. The food waste that went into the pile around the same time is almost completely decayed. I'm not so sure that the average person can compost their Sun Chips bag...I guess I'll wait to buy more until I see some more break down of those bags.