Credits take 3 business days…..Really?

Why is it that when I make a place a debit transaction to a business for goods or services, I immediately see an authorization transaction on my account... However, when it comes to a credit (for a returned item or an ACH deposit) it takes up to 3 business days. Really? We live in the age of instant account communication. This should all be INSTANT! Banks will gladly charge a fee for a "wire" transfer that is complex to execute and is still not instant. It should not take 3 business days to move money from a savings account to a checking account, or receive money from another party. It is instant for debits, why not credits?

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