People mostly drive based on their comfort on the road. Have you ever been behind someone on a single lane road who is going slow but when the road widens to two lanes and you try to pass, they suddenly speed up?
It's (usually) not because they are trying to race you or they're being an asshole. It's because the wider two lane road is usually more comfortable to speed up on so they do. And chances are they don't realize they are doing it. It's very easy to adjust 10 km/h without even realizing.
Look at it this way. A drivers comfort is based on their own skill level, their vehicles capabilities, the road conditions, the weather, and the traffic around them.
It takes actual effort to go slower than you are comfortable driving. It makes you more likely to make mistakes when you are having to force yourself to drive slower than you are comfortable with, just to be under a speed limit.
The problem drivers are the ones who overestimate parts of their comfort. They overestimate their skill (maybe they're drunk or just stupid), maybe they think their car should handle like a sports car when it isn't one, maybe they think the road isn't as slippery as it is.
Those people wind up feeling more comfortable than they should and therefore drive much faster or more recklessly than they should.
Anyways, feel free to disregard everything I am saying as being plucked from thin air. Have a great day!