I love how everyone is thinking that credit card payments are instantaneous. They are not, though are faster than paper checks. The existence of the greyed out pending transactions when you log into your credit card website should tell you that.
It depends what you mean by "instantaneous". As a merchant, I will be instantly guaranteed, by the bank, that payment will be made. The default risk of a major bank is far, far less than the default risk of some random stranger, so it is an appealing proposition.
The risk of non-payment or incorrect authorisation is passed from merchant to bank, something which does not happen with a cheque or debit transaction. So, in effect, from the merchant's perspective, it is instantaneous in terms of a payment guarantee. The actual $$ landing in the account may take a couple of days. (Note that if the transaction is fraudulent, the bank may attempt to reverse the transaction, but if it is unable to do so, the cost is borne by the bank, not the merchant at this point)
From a customer's perspective, it may not be considered instantaneous as it may take a couple of days as 'pending' before the bank verifies the legitimacy of the transaction.
In that context, I would absolutely issue a payment receipt upon a successful credit card authorisation, but would NEVER do so on a cheque or debit transaction (be it direct debit, funds transfer or debit card) until the money has cleared in my account.