First thing is probably just that the US incarcerates a lot of people. So, IF it has wrongful imprisonment at a higher rate thay doesn't help. Which, it might not. US news gets more attention in general and is in the spotlight more than any other country so it could just be a false impression. But, it wouldn't surprise me if it was true.

More people gives you a higher chance of it happening. And beyond that an overstressed system(which the US's is) breaks down more. People too poor to afford their own lawyers get overworked public defendants. Judges with too many cases on their schedule want to keep trials moving along and prosecutors with too many cases push hard for plea deals and use scare tactics to sometimes even get innocent people to plee guilty just for a guaranteed short sentence.