^ Another thing to remember is that machines do a great deal of work for people. For example, all of the work that involves running computers and doing paperwork could be done by a computer without any human operator, at least not in the 21st century sense.
Replication technology decreases the demand for industrial labor and advance computer technology decreases the demand for clerical labor. Since most modern vocations would nolonger be something that most people engaged in, it seems probable that work traffic would constitute a much smaller percentage of total volume than is true today.
In theory, most of the population has so little to do that it has the free time to pursue the level of technical knowledge necessary to make Starships and space stations a normal part of the economic product. It seems quite probable that beyond scientific institutions on earth, universities, and some cultural amenities, most working people nolonger perform their work on Earth, and are instead assigned to Starbases, outposts, colonies, ships, or other off-earth endeavors. What this amounts to is that people on Earth in the 24th century may use the entire planet for little more than recreation.
Of course, I am drifting from the original topic, and I don't want to do that too much. The question of domestic spacecraft does enter into the equation at this point however, and more especially, (A) where commuter spacecraft are docked and (B) the convenience with which earth people are able to transport to them.