When will this type of thinking disappear? You don't need 3 to 6 confirmations on normal transactions. Nobody will double spend a transaction for anything less than hundreds of thousands of dollars because the recources it requires are too big.
Also, even exchanges accept deposits in 1 confirmation. If they can do it, with generally bigger valued transactions, surely a sex worker could do it. Make payment, go for it, and before leaving the transactions is checked. It will have atleast 1 confirmation by then.
It is true that I have not seen transaction with at least 1 confirmation being rejected subsequently. However, why is Coinbase insisted on 6 confirmations before you can spend the coins you have received? Maybe there is be a valid reason?