Second the market masters did not do their research. Being so close to Portland, which has recently published a study on the topic (http://www.pprc.org/research/rapidresDocs/biobags.pdf), I would think that they would have at least looked on-line to see if bio-degradable bags really are "green". The truth is bio-degradable bags will not decompose in the land-fill and require a hot active compost pile to decompose but since they take so long to decompose many commercial compost pile ask that people do not place the "bio-degradable" plastics in their compost bin. Bio-degradable plastics contaminate recyclable plastics if recycled. Also, when these bags decompose they release green-house gasses including methane which is 5 time worse than carbon-dioxide and I thought part of being "green" was trying to reduce these emissions while becoming sustainable. Do you think paper is better than plastic? Think again paper requires about 80% more energy to make, 98% more energy to recycle and cost a lot more to transport due to how heavy a paper bag is compared to a plastic. It also causes us to destroy precious trees which plastic does not. A better option would be to move to a plastic that is created from a renewable resource while not contaminating our recycling which has been on an increase the last few years as people start to think oh yeah I should recycle this instead of throw it away.
For more information just search the internet.
Also look for information about what has been found in landfills after x number of years. Some examples: 5 year old lettuce and 30 year old news papers have been in landfills with little to no degradation. In order for stuff to decompose it needs the right conditions and landfills do not usually provide enough oxygen to do anything.