I think "cause" is a little too one-to-one. If you say something causes something else you're mostly saying that that's the only thing. "Drive" just means that it is the most important factor. Not necessarily in terms of providing the force but possibly in terms of directing. To give an old fashioned example, you might have a 500W amplifier with a 750W power supply, but the output is being driven by a millivolt/microampere signal on the input.