Where I live in Wales slow drivers are a problem at this time of year. They crawl along roads designated 60mph and they often do 30mph or below. They are usually tourists and act as if everyone else should be on holiday too. However, when I go to Scotland and drive, on roads I don't know, I too drive slowly. The difference is if there are cars behind me I pull in at the earliest opportunity and let them pass.
SatNav has also made the problem worse. Tourists are sent down narrow country lanes they wouldn't normally know about or even attempt to drive if they knew what bends and constrictions were ahead.
The worst offending tourist I ever saw drove up one such road and ended up with a queue of cars behind. As we neared the top of a hill, he stopped, blocking the road completely, and got out of his car to take pictures of the town and bay he had just left. He could not seem to understand why the other drivers were so angry. His face was a picture when one (normally very placid) nurse threatened to insert his camera where the sun don't shine. The fact that people live in these towns and have to get to work didn't seem to cross his mind.