What Marcos Alonso did had worse consequences than what Greenwood is alleged to have done. But I don't think it's the same situation, morally.
Him and his friends went out partying and drinking, they all chose to get in that car, and the person who died was not wearing a seatbelt. Although he is primarily responsible, everyone involved had some degree of culpability, harsh as it sounds. He went through a legal process, in which he never denied wrongdoing, and instead of receiving a jail sentence, he had to pay fines, plus additional money he paid to the family ('voluntarily'). This is fairly common in Spain, there is a discussion
here in which Spanish people don't entirely disagree with what happened.
After that you're basically left with a discussion on whether someone who admitted wrongdoing and was convicted should be rejected from society.