Right wing violence (which includes neo Nazis, fundamentalist Christians bombing abortion clinics, etc) and fundamentalist Islam attacks make up the overwhelming majority of political violence in the USA but left wing violence exists. And of that left wing violence the majority is what they call “ecoterrorism”

It’s not obscenely common (tbf no political violence is “extremely common” in America, statistically still very unlikely) but it does happen. It’s just far less publicized because “some people bombed an oil transport line/hummer dealership at night/etc” is not nearly as clickbaity as “weird scumbag with a manifesto about great replacement theory posted to 8chan shot 35 people”