Landmines are an excellent way of defending a wide area for very little money. They permit the defence of an area without requiring large numbers of personnel. This is a legitimate aim both in warfare, when military personnel are spread too thinly to protect all civilians and in poor countries during peacetime, who would rather invest in their infrastructure than funding the military capacity that would otherwise be required to defend the same ground.  They can be easily removed, but not quickly, which is what provides their military utility.  The fact that landmines can be easily removed (if someone actually goes about that process) highlights the real root of the suffering caused by landmines – it is the on-going military conflicts which prevent removal and cause more mines to be planted which are the true cause of civilian suffering. If those conflicts ended then the harm to civilians would dissipate anyway.