They're a problem for me too. They recently chipsealed a high speed road that I ride 2 miles every day, so for about 8 weeks there were no markings on it other than the little plastic yellow tabs they put down the middle. The lanes are something like 16 feet wide, plenty wide enough for even a semi truck to pass me within the lane, but people would just refuse to pass. This is a 50 MPH speed limit road, typical speeds are 55 to 60 MPH.

Finally last week they repainted the lines, and it's now easy to see that I'm in a shoulder (there's a good 2+ foot clean shoulder) and most cars just pass me, though once in a while one will still slow way down before passing me within the lane.

It's particularly a problem near the end of it because I need to turn left into work. If people keep slowing down, they build up solid lines of cars that I have trouble cutting across. If they'd stay up at speed there would be big enough gaps to get over.