I'm not sure what's happening. I created a private network and started mining it.
When the mining is started, the coin base is getting the block reward ( with no transaction).
Things change when I connect Ethereum wallet with this IPC. When connected, the coinbase also gets some transaction fee ! I have no Idea what kind of transaction is done by Ethereum wallet, but it executes state transition function with some transaction involved :
However I don't see any transaction fee added to accounts while mining only blocks
I figured mist is sending 0 value transactions. I have no idea why. That is why they are not reflected in the block.