Automobile dependent communities use cars for different many things. From daily personal transport, to rendering services - like police and ambulance; from transport of goods, to garbage collection and postal delivery. Just because we do not personally drive it does not mean that our community is not dependent upon the automobile.
Automobile dependent communities, are strangely stunted in their potential - limited in location; layout; traffic flow potential; vulnerability to attack; damage caused to the environment and other. Most towns and cities of the world are automobile dependent communities. Only those self-sufficient rural homesteads - isolated and without many "modern" conveniences - or small primitive tribal villages are not automobile dependent.
What are the drawbacks?
1. The automobile dependent community is limited in the terrain that can be used for the community because roads must be constructed. Roads are not easily built on mountainous land, coastal flood plains, river areas subject to flood, or heavily vegetated land. Human communities could easily exist on such places, but needing roads suitable for cars means we tend not to use these areas of the planet.
2. Communities that require automobiles are fixed by how the roads connect the parts. The road is the "artery" that determines how the community is connected and its layout is forever limited. Communities built on water, in the air or even on snow are not so limited by the road since other forms of transport exist that do not require a fixed "road" be constructed.
3. Communities that depend upon roads suffer traffic flow and congestion. Roads create bottle-necks of traffic flow. Communities dependent upon fixed access paths will always be vulnerable to congestion and deadlock as roads reach the capacity of vehicles that they can carry,or certain key parts of the network become overloaded.
4. The automobile dependent community is vulnerable to attack. The community could easily cease to function should road networks be blocked or destroyed. As with communities that require fuel or power for transport the communities are always vulnerable to that power or fuel not being available.
5. Automobile dependent communities damage the environment. Environmentally the automobile dependent community leaves a big footprint. There is a damaging impact upon the world from the creation of roads, tunnels and bridges. There is also the damage that pollutants from the vehicles cause. Even electric cars have an impact on the environment as they are constructed,
One day there may be other transportation options beyond what we currently imagine. We may have personal solar powered helicopters that whisk us across the planet, we may enjoy water-bicycles that propel us from one polar-cap island to the other or we may have harnessed some physics yet unknown.
Until we have evolved to that extent, it is paradoxically those communities that we now label "primitive" which are the most advanced because they do not experience the drawbacks of depending upon the automobile.