How are US cars not safe? Do they spontaneously combust? Break down in the middle of the road?

EU legislation requires a number of design considerations for pedestrian and cyclist collisions, like specific energy absorption requirements for front-impact and side-impact protection, restrictions on sharp corners/steep angles that could concentrate impact forces, minimum clearance around hard internal structures, mandatory ADAS (automated emergency braking, lane departure warnings) etc. Not saying that US cars are "not safe" in a binary fashion but for the most part these things are either optional or unregulated in the US.

Did you even read the article?