The homeowner insurer may require UL approved stove. Did when I was in the business.

Its probably a mix of reasons

Some possibly needed
Some Not

There has been a push to ban outdoor wood furnaces. Yes , they do burn a bit dirty. This is the ' reason ' to get people and politicians to ban them. However , I would bet big utility companies are bankrolling this push to ban them. Think about how much you spend each year on heat/hot water. Then think how much everyone on your street spends in a year , then think how much everyone in your town/city spends on this. We are talking HUGE amounts of money utility companies could lose.

Read a story about a guy that bought a much bigger outside wood furnace than he needed. He took the excess hot water and ran it through a boiler , made steam. Ran the steam through a turbine connected to a generator , made his own heat , hot water and electricity. Powers to be found out , shut him down claiming he didn't have the proper permits.

What about the Smokie Mountains?

*Plan ahead to Vote!*