I have heard of miners making much less than the block reward and I had assumed they were being paid also for processing transactions which would be potentially many small amounts.
However, if these transactions are associated with the block to be solved, then it seems they would make the block reward PLUS the transaction fees -- a miner could never make only transaction fees.
Or are the miners who make a few dollars a day doing so via a mining pool?
Note that I do understand a miner is likely to make zero because mining is very competitive so what I might have expected a miner to have occasional big wins of 6.25 BTC (plus transaction fees) or exactly nothing.
But I think of the example of the guy in Guatemala who burns used cooking oil in a generator and supposedly makes 200 month -- does this apparently steady return of 200/month imply he is part of a mining pool?