system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why on open highways do drivers generally drive in clusters? Usually someone blocking left lane as well.
gpt
If you drive faster than average, you will eventually reach the back of another group of cars. Until you can overtake, you just added to a cluster.

If you drive slower than average, eventually other cars will reach the back of you. Until they can overtake, they just added to a cluster.

If an obstruction or problem appears, causing several drivers to all slow down, a cluster is almost guaranteed to form behind them, until everyone can speed back up and then let the fast drivers overtake the not-so-fast drivers.

Only by all driving at the same speed, or by making overtaking so easy that it always happens right away, could we prevent the natural formation of clusters.