You’re still widely speculating and ignoring some very plausible facts. The pedestrian could have been hit by a joyrider in a stolen car who of course will always ignore the motoring laws altogether regardless of how strict they are and how strictly they are enforced. There could have beeo other circumstances that would have exonerated the driver of any wrongdoing, or failed to prevent the fatality if the driver had been travelling below 20 mph. We simply don’t know at this stage, and trying to assert blame at this stage without knowing all the facts seems rather wrong to me. But each to their own.