Ever thought about what is the #1 problem all countries face? I searched and multiple sources said that an economy's number one problem is scarcity. There is an unlimited demand from humans but there are only limited resources. It becomes now a problem when the government has to answer these questions:
1. What to produce?
2. How to produce?
3. Whom to distribute the product?
Every country is formed on bunch of trading centers which formed pretty much self sustaining network. But these days, to trade between other countries, demand can be bigger, or already saturated so that it's cheaper to just buy it from other countries then produce.
I don't think that the scarcity is a problem there's more then enough for everyone. Problem is that there's 4 people in the world have more wealth then rest of the world combined. And that there's this expectation of ever expanding growth, which isn't sustainable.
Some government decide based on wealth. If you are rich, you get the best products or services. Some governments distribute it equally or based on needs but this usually happens in totalitarian authorities. Some governments mix it up and give some to those in need but also to those who pay taxes the highest.
There is a lot of reasons why this problem can't be solved for good. One is that there will always be needs from people. The population keeps growing and growing. The resources keeps on dwindling down. Not to mention corruption. Will there be a time where we would all have to literally fight for resources?
In all noteworthy governments a rich people / ruling class gets to buy best products. It doesn't matter if you live in social democratic, republic nation or in authoritarian regime / communist society where the wealth and power is centered to small group of people.
And we have been already fighting for the resources since the start, it's just not make sense for individuals to fight for them anymore, as it would just destroy countries from inside. Together we are stronger, so it's the countries that fight over them.