How would it help at all? They've already proven willing to break the law with the straw purchase.
> All of these would stop repeat offenders, and if I recall, the majority of straw sales are repeat offenders knowing they don't get in much or any trouble buying guns this way.
You don't know what you're talking about. It's a felony, and precludes you from purchasing or even possessing a firearm ever again. It's not possible to be a repeat offender.