No, entering your PIN number in reverse at the ATM does not call the police.

It wouldn't be much help if it did. You'd still get robbed. The robber would probably be able to dash off before the police arrived. You're not any better off than you would be if you called 911 once the robber is gone.

Many new ATMs have cameras on them, and I would assume that those cameras record all transactions. So there's basically no benefit to implementing this.

I figure that the ATM makers and the banks figured this out long ago.