The key here is traffic FLOW. Get out of the passing lanes!

If you're on the motorway, and you're being law-abiding, doing the speed limit, and everyone around you is going 10mph faster than you, then believe it or not, you're the problem, not them. In fact, in that scenario, YOU are the one breaking the law.
Across the US, there are four different regulations for the left lane - and when you should leave it. The image here shows laws:

A summary of the state-by-state laws in America can be found here. The same laws are true in most countries - you only use the outer-most lane to pass, then you pull in.

Traffic safety has everything to do with the FLOW of traffic and not much to do with the SPEED of traffic. In low-speed areas, if you drive too slow believing you're being safe, what's likely happening is that you're irritating the people behind you. (Remember: if there's more than one lane, and you're in the outside lane traveling below the speed limit, you're the one breaking the law).
You might think that you're doing some sort of civic duty in trying to control the speed of the traffic, but that's not your responsibility. Your responsibility is to ensure that, as part of a collection of drivers sharing the same road, you do your part to ensure everyone is as safe as possible.
10% of accidents happen during passing or changing lanes. By trying to be the morality police, you're enticing others to try to pass you. In a two-lane scenario, people WILL pass you on the right - which in some places is illegal and in others is not advised. In this scenario, the fact is that you are part of the problem, irrespective of what you think.
The key issue here is difference in vehicle speed, not the speed itself. If you're driving slower than everyone else, you're presenting a 'rock in a river' scenario where everyone else encounters you at speed and has to either slow down or pass you. This difference in speed is what reduces the time available for other drivers to take evasive action. That leads to accidents. If you speed up, the difference in speed between you and everyone else drops, the time for others to see you and take evasive action increases and the accident rate drops.
Around where I live, they recently upped the speed limit from 65 to 70 in the motorways around the city. It went up from 70 to 75 on the outskirts and from 75 to 80 in the rural areas. The news was full of panicky people telling us how this was going to cause a horrendous increase in accidents, and how could the police and city be so irresponsible, and won't somebody think of the children?
Naturally, as often happens when speed limits are increased, the overall accident rate actually went down. Significantly.
But why? The change encouraged the slower drivers to speed up. Previously, the limit was 65 and everyone except the law-abiding drivers drove at 75. By increasing the limit, the overall speed remained at 75 but the law-abiding drivers increased their speed to 70 - meaning the difference between them and the rest of the traffic halved (on average).
If you want to see how clearing the left lane works when done properly, and why speed isn't the issue, look to countries in Europe. In places where left-lane etiquette is obeyed and enforced by the police, the accident rates are significantly lower. For example - in the US, the accident rate is about 12.9 deaths per 100,000 vehicle. In Germany it's 6.8 - nearly half. Remember in Germany there are still long sections of motorway where there is no limit. Even in countries where the speed isn't unlimited - countries like England, Finland, Switzerland, Norway, Denmark, The Netherlands, France and Australia - all these countries have super strict left-lane laws and all of them have fewer deaths per passenger-mile than the US.
But what about the police?
Generally speaking, unless you're being a total dick, the police aren't going to pull you over for keeping up with everyone else on the road. They're more concerned about the overall safety of the volume of traffic than they are about whether you personally are doing 75mph in a crowd of thousands of other cars all doing the same speed.
So please pay attention to the overall flow of traffic when you're driving. This includes everything from speed on motorways to making sure you merge smartly with city traffic when pulling out from side street (ie. don't amble into a 40mph traffic flow at walking pace - speed up and keep up). If you miss a turn, go on to the next one and turn off there and figure it out - don't jam on the brakes and force everyone to stop (and potentially rear-end you).
Oh - and get out of the left lane when you're done passing. And if you're not passing, just pull in.