Vehicular Cycling is the idea that cyclists should operate on roads in the same way that cars do. This philosophy has hopes that if cyclists operate this way, vehicle users will view them as legitimate users of the road.
In theory, this philosophy makes sense if cyclists share the road and use signals as cars would then drivers might start to view cycling at the same level of transportation as a car. The huge issue is that you are now placing the responsibility of safety among the cyclists. Human behavior behind a vehicle can be unpredictable and if cyclists must now ride amongst the big dogs, they now have to navigate around dangerous traffic conditions.
In the Netherlands, there are roads that are shared spaces with vehicles and cyclists. Except in these shared spaces the cyclists are not operating as vehicles, they are operating as cyclists and the vehicles yield to them. As for streets intended only for vehicles, cyclists are separated with cycle tracks and protected by cycle traffic lights/markings.