I know that too and can cause fires if not careful depending on where they land. Someone in Wisconsin got hurt from fireworks 6 days ago in the hands and stomach area. The fireworks were large despite the size being illegal in Wisconsin.
They City I live in had 2 police officers injured from fireworks last night. What happened was someone threw powerful fireworks at them.
The city I live in banned shops from selling fireworks and people shooting them off unless you are a professional. They banned them because of potential of people getting killed or hurt from fireworks. What I mean by professional is the people the city hires for lighting them off in parks, lakefront, or special events. What I mean by special events is if the local sports team wins something big, fireworks shot after festival ends, or a race is finished as examples.
The state law allows people to buy fireworks in Wisconsin, but you need a permit to set them off in the backyard. The ones allowed are toy snakes, sparklers less than 36 inches long, stationary cones and fountains, smoke bombs, caps, noisemakers, and confetti paper with less than 1/4 of explosive mixture.
Also some types of fireworks are supposed to be illegal in Wisconsin. The ones with the big explosions are supposed to be banned, but heard them last night.
They way Wisconsin fireworks laws works is where you live in the state has the right to ban all of them unless you are hired to light them off by government officials, or organizers of special events.