That is why you drive to conditions. On a interstate quality road 70 mph is fine . Unlikely to have pedestrians jump out in front or traffic coming from a side street. In busy neighborhoods you drive to conditions . That doesn't mean flying down at 80 mph on a winding residential neighborhood street.
Oh, you mean clear, dry, wide open road right? 70 or 80 mph, no problem.
What happens when the average guy blows a front tire at 80? Or when the guy in the number 4 decides he wants to be in the number one where the average guy is doing 78 mph?
Drive to conditions means nothing, as those conditions can change in a split second.