However, the Corallo Relay Network does support a sort of compression. Rather than transmitting all the transactions in a solved blocks, since most the other miners know about them already, it just transmits indices that refer to each transaction (sort of like a map for how the TXs fit in the block).
I think a more appropriate term for this would be encoding - using codes to represent larger blocks of information that is already known by all parties. This is usually way more effective than blind data compression.