That is just not how the human mind works. It protects itself from unpleasantness when it can (but that is a totally different discussion on psychology)

All I am saying is, don't bargain on it that he would punish himself more than the courts would.

Lets put it this way, if your best friend left your child in that car. What punishment would you want for him/her? If your answer is honestly none, then good. You are a better person than I am :)
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Extraordinary claims require extraordinary evidence - Carl Sagan