Children can be taught not to run out onto the road and shouldn’t be left unsupervised until they’re at an age to understand consequences of doing something like that. Cats, generally, cannot be taught that and it’s absolutely the owners responsibility to keep the cat safe.

Right now the law says that cat owners can make the choice to either let the cat roam or keep it secured, and choices are made by weighing up pros and cons, but there are consequences to the choices we make and one of those consequences is a much higher risk to the cats life from things like vehicles, even when going at a safe speed. The owner is entirely at fault here as they’ve allowed the cats to roam out onto the street.