I see this argument in response to keep right rules all the time. Do people really think it means everyone is in the right lane at all times and never moves out of it for any reason? It's not that extreme, even in states like Maine and Massachusetts that have the more strictly worded laws.

Faster traffic uses the left lanes to overtake slower traffic, and then moves to the right when they're done. This is how it works in the majority of the world that drives on the right. In countries like the UK where they drive on the left, it's the same system, but reversed.

Heavy, but free-flowing, traffic means a speed gradient between the lanes: Right lane moving the slowest; left lane moving the fastest; any lanes in the middle should be progressively faster as you move left. As long as each lane is moving faster than the lane to its right, the letter and spirit of the law are being followed. The people getting pulled over in this situation are the people who are obstructing traffic.

Stop-and-go traffic, nobody is getting a ticket for failure to keep right. Nobody cares what lane you're in when it's stop-and-go. Just keep it between the lines and use you blinker if you need to move to another one. If I'm the one in the other lane, I'll let you over in front of me as long as I see the blinker.

These rules are not about letting people use the left lanes as a racetrack, or about parting the Red Sea in heavy traffic so that people can do 100 in a 70. They're about creating an orderly, predictable traffic flow so slower drivers and faster drivers can share the same road safely.