In Space Jockey, Robert Heinlein showed us a (roughly present-day) world in which commercial rockets routinely brought paying passengers and cargo to the moon, but the machines that plotted the trajectories were much too large to bring on board.
In the real present day, of course, you can plot a trajectory to anyplace you like with a machine that fits in your pocket. What you can’t do is actually go anywhere.
Where did the portable trajectory-plotting machine come from, and what happened to the rocket that was supposed to go with it?
I am firmly convinced that the answer can be found by comparing and contrasting the laws and regulations governing rockets (and high-density energy sources, on which rockets inevitably depend in the absence of wormholes big enough to send real power through) and those governing computers.