I have a question on mining operators. How do we know they are declaring 100% of the found blocks to the pool? Couldn't they simply skim a few blocks to an unknown entity once in a while?
Is this 100% based on trust?
In order to solve a block that pays someone else, a mimer needs to mine a block with a coinbase address specifying where the block reward should go. This would mean solving a block different than the pool gave you, and would not count as a valid share on the pool, decreasing your hashrate on that pool. Therefore this is equivalent to splitting your hashrate between multiple pools. (Or partially solo mining)