It's owned by who is in possession, so it would be the banks. A receipt is irrelevant, they could never make one. So, if the cash is in the ATM tray it's on the banks premises and in the banks care and possession, especially if it had been counted by the ATM and was being processed. If it were just sitting on the ledge of the machine it's still the customers responsibility.
The amount would need to be confirmed before they deposited the money, not after they handed the money over. Just like giving money to a grocery clerk or bank teller, you can't demand it back unless they agree to return it. Like at a casino where they count in front of you at the cashier. You can disagree with the count, but you can't demand the money back, it's in their possession.
In this case it looks like the ATM agreed to not accept the money because the depositor did not confirm. However, no response is not a confirmation either way. The money was still the banks. The money should have been accepted, then the depositor would need to dispute later on if it was deemed incorrect.