The US version (varies by state) of the fast lane is garbage which is why nobody follows it. If you want a passing lane then you need a non passing lane and I don’t think US drivers are willing to make that concession.
Then why the f*ck are they in the left lane?!
Most of them go back to the right/slow lane when they're done passing any trucks and other slow traffic. Even on the I-5 it's not like the right/slow lane is an unbroken line of trucks from Mexico to Canada, you know.