an accident or road construction...+5.

Fear. I suppose there are a small group of people that do it deliberately just to annoy the hell out of everyone else on the road, but the majority of people who do it would do it out of fear. Fear of an accident, fear of getting a ticket, etc.

Maybe they are wearing their beer goggles. That makes people drive extra slow/careful.

They're not in any hurry to get anywhere.

Because you are driving right on their butt - the closer you are, the slower they go.

They don't want to lose their license from getting a ticket or having an accident.

Some people only drive at a speed they feel comfortable and safe. Their limits are much lower than the average driver. I can't fault them for not driving faster, better than having an accident. I just wish they were not in front of me when I have places to go.

because i dont have the 200 to 1000 dollars for a ticket... call me old fashioned but tickets just arent that cool

These are drivers who, for the most part, lack confidence in their own driving skills. They simply don't drive "automatically" as most of us "too-confident" drivers do. They just never got the "hang" of it, so to speak. Their minds are on every vehicle on the road, every traffic sign, every signal...while ours is on things like what to fix for dinner. If you wanna see people drive slowly, hitting their brakes every other second, drive in a southern city when there's a mere "dusting" of snow! Enough to drive ya nuts! +5

There are many reasons for that. I'm more worried about the reasons for not doing it: very few kids get driver's ed anymore. When I was in high school, we had ridiculously low standards for getting a driver's license, but they were higher than the standards now. We were expected to actually know the driver's manual for our state inside and out. We had a twenty question test to pass as well as a pretty rigorous driving test. It was not uncommon for kids to fail the written test several times before they got their license, and their were several tests, so you couldn't just memorize the answers for the next time. The next time you got a different test. As such, we actually had to know all the driving laws for our state. And in driver's ed, we learned a lot of the physics of driving a car. Just the controversy over SUVs and pickups being easy to roll brought it home to me that kids don't know how to drive anymore. We learned in driver's ed that any car with high clearance and a high center of gravity must be driven slower than a low one. Its just physics. If you don't want to drive slower, don't buy an SUV or small pickup. So here are some reasons for driving below the speed limit. 1) As you age, your eyesight dims. At about forty, you are going to need bifocals. Your eyes also start needing more light to see the same things. If you can't see as well, you need to drive more slowly to give yourself time to process and react. And yes, older drivers do have a right to drive and we still need to respect our elders. 2) Weather conditions. Even the slightest bit of rain lubricates the road so that your tires don't grip as well. That is just physics. You need to knock about 5 mph off your speed when it rains to allow for this effect. When it rains heavily, there is the risk of hydroplaning or of having someone suddenly splash ten gallons of water on your windshield, so you should slow down a bit more. Snow is a bigger factor. Just because you can go, that doesn't mean you can stop. You have a responsibility to everyone else on the road to have your car under control. Those people in the cars around there are not there just to annoy you. They are people trying to get home to their family just like you. They are loved. People will mourn if you kill them because you were in too much of a hurry to slow down. 3) There is something wrong with their car and they are trying to get to a garage to get it fixed. 4) They have a load on board that makes their center of gravity higher or may shift, such as a horse or large dog. 5) They have an awkward load on board that can't be tied down well or they haven't bothered to tie down well. I have serious objections to this too. You don't have the right to risk the lives of the people around you because you are too lazy to rope something down. I only know of two reasons for driving too fast: you have a bonafide emergency on board, such as someone in labor and crowning or you are in a hurry, left too late and value your hurry more than your life or the lives of the people in the cars around you. That is just selfish.

Usually when they notice a law enforcement vehicle nearby, or their hair is blue (waiting for trolls on that one), or the car has dark-tinted glass with smoke billowing out the windows as loud Bob Marley music is thumping from their "kickers". :)

Too many variables for a good answer. Timidity or lack of self confidence are possible. Fear of the law is another. Unfamiliar roads, unfamiliar car, anxiety, bad memories of an earlier crash? Age may be a factor. People who learned to drive horse-drawn buggies tend to drive at a horse-drawn speed. Neither my mother nor my late father-in-law ever exceeded 40 miles per hour. I'm sure they must have killed people who tried to go with traffic flow.

It could be their car. I had a car that was hard to get past 40 mph

Some are afraid of driving but have no other way to get around. Some have poor driving skills and realize it and want to give themselves more reaction time. Some believe slower is safer which isn't always so if it disrupts the flow of traffic but you can never tell them that. Some just aren't in a hurry. Some believe it is there duty to be 'keepers of the speed' and slow all traffic down that is behind them. etc, etc, etc.

usually rubbernecking

Bad drivers, plain and simple, for so many different reasons.

Whenever I drive slow it's because I'm not paying attention to my driving.

Well I see a lot of old people driving extremely slow so being old.

Knowing that the wife is home.............

They are simply incompetent and or inconsiderate drivers, and not enough is done as far as giving them tickets for driving in a proven unsafe manner. Driving way under the speed limit can, and does cause accidents just as driving way over does.