I've lifted the following paragraphs from the Beyond Intractability website. It succinctly explains why some people bother to do difficult stuff for another country.
Particularly since the end of the Cold War, it has generally been taken for granted that democracy is the best political system, almost regardless of the circumstances. Once warring sides have reached a ceasefire, democracy is seen as uniquely suited to provide a peaceful means of competition for power and influence. However, opting to go the electoral route is not without risks. An important advantage can go to those who win foundational elections. The stakes may seem extremely high in future elections as well, providing strong incentive to opt for extra-legal means to ensure victory. It is in these delicate situations that election monitors can play an important role.
Monitoring is important because elections are the cornerstone of creating a democratic political system. As such, monitoring can assist democratic consolidation by instilling domestic and international legitimacy. Peaceful elections may also promote reconciliation between former adversaries. Postconflict societies, however, are often poorly equipped to conduct elections. Despite a formal end to the fighting, instability often persists. A continued lack of security makes campaigning difficult, to say nothing of actually conducting a vote. Institutions needed to conduct elections are often nonexistent, or damaged by the conflict. Where contentious elections present fears of vote tampering and other irregularities, the presence of election monitors may serve to prevent shenanigans and give parties greater confidence that the vote was free and fair. The key to achieving this outcome is monitors who are seen by all sides as neutral. Because of this, monitors are often foreigners that arrive prior to the vote at the invitation of a sovereign state.
Monitoring can enhance the credibility and legitimacy of elections, thereby helping to reduce electoral violence. It can help maintain a working peace agreement because losers lack the ability to shout "fraud!" and disrupt a country's democratization. One way in which monitors do this is by taking independent vote tallies, which prevents governments from manipulating the vote. Even before this, some monitors arrive long before the vote to observe campaigning and voter registration efforts. In addition, foreign funding contributes to planning and conducting the vote. What is more, it can provide technical expertise and training for locals who may never have conducted an election before. As such, in the long-term, monitoring can assist in building and strengthening domestic electoral institutions. For example, over 50,000 Cambodians were trained as election officials by the UN Transitional Authority for the 1993 elections. Finally, it can also help in the long-range development of political parties and civil society.