The thing of it is that in this case there's only a 30 40 second window involved the time it took RH to strap Cooper in his car seat and give him a kiss at the restaurant and then drive to the intersection where he went straight instead of turning. Also, when he parked at HD he sat in the car for another 30 seconds so he'll have to claim that Cooper fell asleep in the meantime.
Furthermore, while other parents who forgot their kid were distracted by something, RH stated he wasn't on his phone at the time nor has anything been released (yet) about a work or family emergency occuring during that time or a change in his normal routine.
That's very different from the other cases. The only thing that RH's defense might claim is sleep deprivation, as per LH's speech at Coooper's funeral and IMO that would be quite a stretch as most parents are sleep-deprived for the first couple of years.
Even then, I can't imagine the legal can of worms such a defense, if successful, would open for future cases.