They should start imprisoning people who “forget” that their child is in the car. Even those for whom it is a lapse in memory. Hard time for each child’s death.
This sort of thing happens. You can forget that you have your child with you when you go to the store. You can assume your spouse grabbed the kid out of the car when you got home.
These cases are rarely intentional and the amount of anguish that the perpetrator feels must be extreme. Locking them up will solve nothing. Parenting classes will solve nothing. Accidents happen, people are fallible.