[thomastjeffery]

You can't expect people to go the same, or similar speeds.

There will always be trucks going slower, and always people who feel comfortable at much higher speeds.

Going different speeds is what multiple lanes are for.

The problem is that multiple lanes lose their value when two cars are driving side-by-side at the same speed. If the left car speeds up for a short period, then moves to the right, traffic will be able to circulate, creating more distance between cars, and fewer instances of significant speed difference in a close range over a period of time.

The problem is that speed itself is quantifiable, so police focus on it way more than is helpful. To legitimize speed tickets, there have been years of propaganda teaching people that slower = better, so those who want to drive slow feel vindicated, and those who understand traffic flow are frustrated.