The uses R160s more than anything else. They sometimes run back to back.
As far as assignments, I believe it uses 8-10 sets of 160s and almost the same for 179s.
On a separate note, is there any reason Subway time shows the running at 8-minute headways when it’s scheduled to run every 4-6? I checked and there are no GOs or any planned work along the line for this weekend. There isn’t the first time I’ve noticed either.
Some folks would rather spend the extra money, use their personal vehicle, or even carpool to reach their destination quicker without being delayed or stuck in traffic. As it was noted, it boils down to comfort and convenience.