In the old miningsystem in Project Entropia there was two types of separate finder: One for ore and one for enmatter. Enmatter used probes which cost 0.5 ped each and ore used bombs which cost 1 ped each. This was changed when Mindark decided to merge the two types of finders, but the cost/ratio difference in searching for each type of resource remained the same.
Why they did not change it to the same cost per resource type I think was probably that it was time consuming to balance out the hit ratio and resource value, so they did not bother with it.
Funny fact on the old miningsystem: You had to drop a bomb on the ground and press detonate. This resulted that some bombs was missed to press detonate so many bombs lay around on the ground of Calypso. If I remember correctly you could not initially pick them up, but that got changed in a VU. Which resulted that some mining runs you could profit some extra by finding bombs that lay around in calypso