

Uh, no?
Riots in France over unpopular political policies are so common that they’re a meme. Saudi Arabia overthrew it’s dictator via political violence. China, Russia, many others have had political violence on a massive scale.
Political violence is common. The only real difference is that–in theory–Americans have the tools to enforce regime change at home, should the citizenry choose to assert that ability. There are literally more guns than people (by a lot!) in the US, so our civil wars end up being some of the most bloody and brutal on the planet. (Roughly 2% of the entire US population died in battle in the US Civil War; US Civil War 2 would almost certainly be worse, since it wouldn’t be limited solely to direct military engagements.)
Single digits, 100%.
Single digits range from -9F to 9F. Triple digits start at 100F, and can go way the fuck up from there. (And with climate change, they will!) Once you start approaching triple digits, you have to worry about humidity, because you can easily hit a combination that’s literally too hot to live.
Is -9F unpleasant? Sure. But you can layer clothing, and that will keep you comfortable. Death Valley has hit >130F, and when that happens people die, even if they drink gallons of water and stay in the shade.