There are many long term benefits for countries to work together by implementing economic standards like the EU Economic Integration. Short-term tariffs often polarize countries away from each other and can international tensions. By agreeing to preferential trade agreements that favor countries by lowering tariffs and establishing free trade through common markets, countries can increase revenue brought in by all involved. Such long term thinking can give countries an economic edge that typically outshine narrow-sighted benefits.
The opposite is also true. When a country chooses to weaken ties with another, they can help de-stable their counterparts economic strength by declaring higher tariffs and fewer trade opportunities. Often the country benefiting most from economic integration will lose power in the face of the changes and is more likely to cave in to political demands.
A very strong form of economic integration is the creation of a monetary union which creates a common union between countries, such as the Euro. Monetary unions help create economic growth by creating an established economic market between the countries involved and give consumers many individual benefits to bring surplus revenue. This is also an international sign of alliance between countries.