[econjack]

This is the same as the steam shovel replacing thousands of ditch diggers. Their labor was no longer needed at any price.

Really? Then why do China and a host of Third World countries still prepare and repair roads with humans using picks and shovels. Could it be that labor costs less to remove a ton of dirt than the capital cost of a steam shovel? (Hint: Yes)

[central_va]

There is a huge difference between the overpopulated and corrupt 3rd world and the developed world. It is a safe assumption that there is no labor rate where human ditch diggers would beat modern earth moving machinery in the developed world. The USA is not the 3rd world even though most economists in the USA are trying to get the USA to that place, a two tier social economic system.