This is what @chris mentioned in another thread.
The telescope doesn't have to be any more accurate than the camera. Same problem...drivers out of our control. Unfortunately to have the accuracy that some need we have to rely on the camera for this time as it's the only one that precisely knows when an exposure starts and ends. We can request an exposure but the precise start time is unknown to us as the camera may take some time before the exposure actually starts. When doing some measurements I believe this is an issue. I just make pretty (generally not so pretty) pictures so this isn't a concern of mine. But those doing scientific measurements seem to need this precision.
Thanks,
Jared