True. Bernie Sanders would be a centrist from a European perspective, or even a right-leaning one, by still favouring capitalist ideas like governments relying on private contractors, commercial health care (even if funded by the government) and unconditionally supporting Israel with weapons and security council vetos.
From a European perspective, Clinton is definitely conservative. She'll work well with Theresa May, even if being even a bit more to the right than May.
And Trump is a wacko right-wing xenophobe, aligned with parties like National Front. And one that seriously scares people, especially ones old enough to remember how much damage righteous nationalists can do when they gain power. Right now, Europeans think that reason must prevail, and that there's no way the American public can possibly vote in someone like that. But history has a tendency to repeat itself.