It’s the mindset difference between DIY and outsourcing, essentially.
Denser populations are used to their biggest problem (and biggest help) being other people. So they tend to outsource more.
Less dense populations are used to their biggest problem being something they need to do themselves, because there aren’t a lot of people all up in their business/available when they have a problem. So they’re more comfortable doing DIY.
The issue in this case of course that outsourcing personal safety puts a lot of power in other people’s hands.
Typically, this results in people in dense areas being more manipulative and avoidant to compensate. You can have a good life by getting other people (readily available) to do things for you. Having certain people be mad at you can result in really bad outcomes if you can’t manage the people around you.
Folks in less dense areas being typically more direct, because they can/need to be. You can have a good life by doing things yourself, and you don’t need to worry if someone is going to be (moderately) unhappy with you. And even if they’re really mad at you, you can do something about it directly without needing someone’s help.
For exteme examples in either direction;
- less dense, say Siberia, Alaska, Sudan - ‘everyone’ is armed, ‘everyone’ knows how to jump their car and fix basic plumbing issues, how to do basic first aid, etc. (at least 50% of the population, anyway).
- more dense, say Mumbai, Tokyo, New York City - only the cops/military and extreme outliers in the population are armed (< 5%) and ‘no one’ (well under 10% of the population) knows how to jump their car, fix plumbing issues, basic first aid, etc.
This has always resulted in tension. Ghenghis Khan was on record for really hating ‘decadent city dwellers’ for instance, and made a habit of destroying any particularly decadent cities he ran across (and either slaughtering their populations or driving them out of the city) apparently out of spite. Large cities have always expended significant effort in controlling who is armed and when (including Rome, London, Paris, etc).
This is directly applicable to US politics, and shows up quite clearly in the gun control debate too, where gun control laws have a clear and nearly (but not completely) 100% correlation with population density.
It’s also something you can see as a clear trend in Europe, with West and South-West European countries being strictly controlled, and less dense Northern, Eastern, and Central European countries being looser.
South and Eastern Asia, being exceptionally population dense, has almost complete prohibition of firearms for civilians. Even air guns are strictly controlled in most countries.