The point of the single rider line is efficiency of the ride, not the customers' experience.
I don't understand why anyone would expect a CM to grab 2 single riders over 2 people in the SB line. The SR line is a supplemental line and is
only there to fill in spots when actually needed. It's just math and sometimes certain CMs work harder to fill in the exact seats before having to grab from the SR line. It's total luck of the draw and there should never be any expectations of how long it will take. It was never set up to get you on a ride faster, most times it does, but again, it wasn't designed for
you, its for the performance of the ride, that's all. Just be happy when it works out