I believe this is because of a Consumer Reports story. As I recall CR said they tested multiple gas appliances and compared their harmful gas output. The only regulations that they found were for outdoor gas grills. The indoor gas grills put out more harmful fumes than the outdoor ones were allowed to put out. They listed the models they tested. I think that there were a couple that on low were OK. On high they required a hood running on high to make them anywhere near safe.
Someone probably read the story and started this push.