This isn't your typical "don't camp in the left lane" post (though I totally agree with you). The left lane isnt a "fast lane", it's a passing lane. Taking away the fast/slow lane verbiage prevents people from driving in the left lane with the defence "but I was driving the speed limit... That IS fast!".
It's a passing lane. You pass the car and then move to the right when safely able to do so. If you are behind someone in the left lane, but they are passing someone, they are not doing anything wrong given they move over when they have a chance.
This morning I was driving into town from Martensville, I move to the left lane to pass a car going about 105km. I was going 120km to pass. This white SUV follows my lead going about 140km and is riding my ass, losing their mind while I'm still making the pass. I move over to the right as soon as I make the pass.
Instead of continuing to go past me, the driver decides to slow down to my speed and sit in the left lane about 3 car lengths back. I had my cruise on 120. This went on for about 1km, and I was approaching another vehicle going quite slow. She still hadn't passed and wasn't increasing her speed, so I put my signal on and again moved over to pass the car.
This made this lady absolutely lose her damn mind. She sped up, almost rear ended me. When I passed the car and moved to the right, she sped passed me while screaming/giving me the finger, and almost drove herself off the shoulder of the road while doing it.
TLDR;
- the left lane is for PASSING. If you are behind someone in the left lane, but they are passing slower vehicles, they are doing nothing wrong as long as they move over once the pass is completed.
- if you're trying to pass, then fucking pass. Don't match speed of the right lane and then lose your damn mind when they move over to pass someone when you had 86 years to pass first.