I know that rolling friction is almost always less than the maximum static friction, but why is this? In particular I am researching why ball bearings have much less friction. It has been said that the ball bearings come in contact with much less of the metal, but this does not make sense to me as friction is not proportional to surface area. So if it has nothing to do with surface area, then why is rolling friction generally much less than sliding friction?
You are confusing "rolling resistance" and friction. These are two different unrelated phenomena, so there is no reason why one should be less than the other.
When the ball bearing rolls with constant velocity without sliding, there is no static or kinetic friction with the surface. The ball is not accelerating so there is no net force on it due to friction.
The ball bearing is slowed down because of rolling resistance, not friction. Rolling resistance arises from the deformation of the surfaces which are in contact, so unlike friction it does depend on the area of contact.