The necessary bulk of the airship for human transportation is a serious crimp in the practicality of such a solution. Technology can't make the bag small enoug

The necessary bulk of the airship for human transportation is a serious crimp in the practicality of such a solution. Technology can't make the bag small enough because it is limited by physics. Even if we could build ultra-rigid and outrageously light bags that could have all of the air pumped out for a vacuum you still need a fairly large balloon to carry people. One person would displace 70 meter^3 of air, not counting anything else. That's not going to fit in your driveway.