The child would not have been legally allowed to use his gun in public places, nor could have obtained a concealed carry license. So as far as the car/gun comparison, they are equivalent since the child couldn't have been fined for driving a car on their property. it isn't until he takes the car on public roads that a license matters. But if you want to torture it further, more children are killed every year in automotive mishaps with legal licensed drivers than gun discharges. Pretending that licensing guns like we license cars will quell gun violence is an apples to bowling balls comparison in the first place, but even if you could strain some sense out of such a tortured analogy you would find that drivers licensing doesn't compare favorably and would hurt your gun licensing argument. Besides which, most states do have a gun licensing law regarding carrying your gun in public places. Some allow open carry without license, but most require a license for concealed carry, and some don't allow open carry at all, effectively forcing all of their armed population to be licensed in order to use their guns in public areas.
You should rest easy at night, Charlie, knowing that everyone around you in Texas who is carrying a loaded handgun is licensed by the state. Unless, of course, you still don't feel safe, in which case you must admit that licensing really means very little in how safe you actually are from gun violence.
None of which is relevant because none of the gun legislation favored by either party would have prevented this child's death.
This is an issue of bad parenting, plain and simple, and quite frankly they are likely not the ones that will suffer the most due to their choice. Chances are their son, the child who killed his own sister, will never truly recover.