Two lanes or one will fit through a 1 lane naroowed section in a perfectly optimized way at the same speed. 1 lane cab only carry "x" cars per second. But by putting the merge at the choke point, we end up with gaps when people hit the brakes to let the other lane in and don't accelerate at the same speed. I lane with 10 ft gaps between cars might get through a bit faster because a perfect merge with 10 ft gaps isn't going to happen. Basically, its the Nagel-Schreckenberg effect except everyone gets stuck slowing to 15mph at the merge instead of merging early and possibly oinng through the restriction faster without issue.

Having said that, there's no mechanism to enforce early merging other than being a good driver (or the unsung hero's who straddle both lanes to prevent cutting). I've given up. If no one else will drive properly, then why shouldn't I drive to the very front and push my way in? I'm just punishing myself by doing it the better way because it requires everyone to participate.

Eventually, we can avoid this by using dynamic signs on a gantry over the road to close/open the lane way ahead of time depending on flow and how far back the line goes.