Earlier quoted context omitted.
I dare you to tell my why lxc-docker silently fails to start at boot in jessie. Without a single shred of clue in any log, no matter what logging options are turned up - at least with a shell script I can add some echo/exit/touch etc. statements to convince myself it's at least being noticed at startup: https://groups.google.com/forum/#!topic/docker-user/bg5-hlmR...
The next step in troubleshooting that one is to run strace and find out what's happening. I agree it's frustrating but if no one debugs these things, problems won't get solved. (and yes, scorching the earth and installing a different distro is a valid solution to the problem at hand)
FWIW systemctl start docker works fine after the system has booted. It's configured to require network.target, and even though I can see network target scroll by during boot, it's still not being noticed.
The work-around is to make multiuser want docker, then I've got docker starting at bootup.