Or do we just assume that any accident must mean "lack of regulation"?

Like every car crash means there aren't enough traffic regulations and there are insufficient traffic cops to monitor drivers. That kind of reasoning leads me to think some would like weekly safety inspections, frequent alcohol check-points, health checkups to keep people that are ill from driving, really close supervision to make sure nobody speeds or has unsafe driving practices. Perhaps monthly driving tests?

Don't know what to do about irresponsible drivers. Even one act of idiocy could cause an accident, meaning there aren't enough regulations. Perhaps on-board computer control, so that if you go over the speed limit, change lanes too quickly without a sensor that says an object is stopped ahead, change lanes without signalling or running a stop sign the DMV is immediately notified and your license revoked until you can justify your actions. (Driving without a valid license could be caught at the next checkpoint a few blocks away.)

Think how insurance rates would drop, once we have enough regulations and enforcement to stop all traffic accidents. Zero tolerance on steroids.

with lack of regulation, or lack of respect for regulations.

Following the fertilizer explosion in Texas, Perry et al said no regulations were necessary.