It seems you're limiting your perspective to recent conflicts. Mines and unexploded ordinance are a huge and long-standing problem across the globe. For example, it is still common for explosives from the first world war, a 100 years ago, to be found in Europe. Similar is true for nearly every other conflict in history.

An interesting point the article did not mention is how some forms of munitions tend to release more identifiable gases as they slowly decay over time. This is one of the reasons why using trained dogs has been effective to locate mines. If they can get this laser and radar tech working effectively, it stands to reason this tech will be especially useful for finding and clearing old mine fields.

Mines are a terrible problem, but tech like this has a chance of saving a lot of innocent lives.