Causes of slow drivers
-Save petrol
-Safer
-Curious people
These are the common ones.
Save Petrol
10 minutes traveling with medium/high speed.
20 minutes traveling with low speed.
Rather save time.
Safer
Not saying you should be fast at all times, but you could be the cause of accidents. Not everyone is free. Some people are either busy or rushing. You, driving slow, causing others to drive recklessly. Judge the road situation and adjust your speed.
Look at the back mirror, look at the cars around you. If you see cars fucking close to your back bumper, cars overtaking you ALOT, you're most likely slow. Be considerate.
Curious people
Staring/Pointing at an accident wouldn't cure/help anything. You want to help. Stop aside, not driving at the speed of 0.0079KM/H then move away. If you still want to know what happen, a glance is enough. Don't bitch talk on the spot while hogging the road.