This is a simple retag request:
driver is the most common, so they should probably be merged into that.
Actually, as a few people have pointed out, drivers is probably more intuitive, so that may make more sense.
When you're talking about [drivers], you're talking about [drivers]. Can't see it being [driver].
device-driver seems way superfluous.
I'm surprised that driver is the most common. I would assume that "drivers" would be the first thing thought of when trying to do a search. Maybe that is just me.