Aug 23, 2016
Yes, Coinbase pays the miner fees on external transactions in order to ensure these transactions propagate throughout the bitcoin network quickly. For very small transaction amounts you may be prompted to pay the transaction / miner fee.
Miner fees are a small amount of digital currency that is included in transactions as a reward/incentive to the people who operate the network. They help the network continue to grow and provide an incentive for your transactions to be verified quickly.
Remember, Coinbase to Coinbase wallet transactions are always free of fees, no matter how much you are sending.
https://support.coinbase.com/customer/portal/articles/815435
I think they are not using Bitcoin addresses for internal transfers. If you send money to your Coinbase wallet, you will soon see that the money gets moved from your address, where you have sent it, to some other address. In this fashion, when you transfer funds to someone else who is also using a Coinbase wallet wallet, the money doesn't get transferred anywhere. I mean transfers that result in transactions seen on the blockchain.