Today Sarah asked me why China is only now building subway systems in all its major cities. I pointed out that non-local mass transit is a capitalist phenomena: totally aside from the fact that you need the wealth generated by capitalism to pay for such systems, there is no need to travel in a socialist economy.
Under socialism, the work unit is the basic unit of social structure. The vast majority of people are born, educated, work, live, and die under a single work unit (a city block, village, or factory). One cannot buy or rent a dwelling (that requires property rights) so one cannot move away from work: the State assigns nearby housing. One cannot change chose or change jobs, so one cannot move work away from home. Housing assignments are hereditary and based on local connections, so it is impossible to move away from relatives: thus no need to travel to see family.
Furthermore, there is no need to travel in order to shop: since all goods are identical commodities sold by identical state-owned stores. There is little demand to travel for tourism either, since all monuments are variations on the same state-promulgated patriotic themes. There is no incentive for entrepreneurs to promote any non-approved attractions – in fact, such activities can be quite dangerous.
Neither is it practical to marry someone across town: the work unit either regulates marriage directly (the work unit leader must approve the marriage) or indirectly: since permission is required to live together and often to have children as well.
Thus, even in places where the State created subway systems prior to the introduction of capitalist elements, they were/are vastly under utilized. In fact, their primary purpose was military defense, not transportation.