Why doesn't getblockchaininfo reveal BIP9 signaling statistics? An example of the output of getblockchaininfo is here:

https://chainquery.com/bitcoin-api/getblockchaininfo

The softforks field describes the number of required / found blocks signaling the soft fork, but the bip9_softforks field does not. It just indicates a generic status message ("defined", "started", "locked_in", "active", "failed").

Is there an RPC command that will return the number of SegWit blocks?
The answer is pretty boring. Nobody did the work to implement it (yet).