"Everyone does it" is an important consideration, if only because making regular people into criminals erodes general respect for the rule of law. "Everyone does it" won't outweigh every harm, but it surely outweighs some.
That's what people who speed (ie: most people) say. "This is evidence we should raise the speed limit". And so we do, and state after state runs studies showing that the result of doing that is traffic fatalities.
