Lawyers talk about malum in se (bad, in itself) and malum prohibitum (bad, because we have prohibited it). I think these are useful concepts, even if we choose not to use the terms.
Mala in se I (tautologically, perhaps?) don't support. For mala prohibita, it really depends on context.
Because they are the rules we've adopted to make society, the markets, contested access to scarce resources, drug safety, or what- have- you work. Sometimes there's more than one set of workable rules, but we have to pick one.
Ideally, because contextually it makes sense. It might not be inherently evil to drive 180 miles per hour, but we might guess it to be statistically unsafe in residential neighborhoods, so we prohibit it.
Mala in se I (tautologically, perhaps?) don't support. For mala prohibita, it really depends on context.