Clearly the guy (mostly a teenager or a jerk) doing 90mph is not going with the flow. I travel a lot and in many different places. Virginia is almost always 3mph +/- of the speed limit and its relaxing. In other states you have the 90mph (going with the flow) zooming around everybody else.What?
For a 30 mile drive 65-80 is a difference of a about 6 minutes. And yeah 6 minutes isn't a ton. For me that difference would waste about a half hour per day. Some days a little less, on my long days, it would cost me an extra 1.5hrs. Admittedly, I could shave 5 minutes here and there and probably make it up elsewhere in life I'm sure.
But flow of traffic again is the concern here. One person deciding to do 15mph less than everyone else can cause accidents. And it's not always the turtle that's involved. It's the guy doing 90 hitting the guy doing 75 in the fast lane trying to pass the guy doing 15 under...... it's less dangerous for everyone involved to go with the flow.