Slow drivers create more accidents on high speed roads than fast drivers.

[OAM]

It depends on your definition of slow.  Driving the speed limit is acceptable.  Five over is acceptable.  Five under is annoying, but assuming there's a good reason, I'll deal with it.  Less than five under you're a terrible person who isn't very considerate, like people who don't use turn signals.  More than five over *might* be okay if conditions are very conducive at the time, IE you're the only one on the road.

What's probably more important, though, is following distance.  At the very least two car lengths if you're not in a downtown area, IE constant stop signs/lights.  The faster you're going, the more following distance is needed.  I drive five over, and wouldn't have an issue with someone doing ten over if they didn't get so damned close.  At least one out of four get so close I can't even see their headlights.

[OAM]

Eh, that might be a regional thing actually.  Around here there are some idiots who are all over the rare, but they're typically rare, in places with little traffic/where it's easy to avoid them, and not doing much else wrong at the moment.

For merging onto highways, some states actually have stop signs at the end of the on ramp, though I've never seen one in person, just photos.

[OAM]

I've seen the stop signs, but I'm not sure where.  I remember the onramps for the PA Turnpike were AMAZINGLY short and that may have been where I saw them.

and Illinois drivers are better than average when it comes to lane discipline....in my experience at least.

The area I was thinking of was when I was google street viewing San Fransisco.  I've never been to California, so I'm not sure if it was a standard feature.  At least that's where I *thought* I saw them.  Now that I think about it I might have seen some in person in MO too.

I'd argue that in IL lane discipline might be high because we're very possessive of our space and might retaliate   To be fair, I've never driven in Chicago, and only been there twice, so my experience is also downstate.