Some are...but usually it is for a situation where:
1) They e-filed Federal separately first, and haven't had their Fed tax return "Accepted" yet. They have to wait for that before they can e-file the state when done separately.
or
2) The state involved isn't accepting e-filed state tax returns until later...a number of states require waiting until later in January....and some state e-file "software" forms aren't ready until after 26 January.