Resources need to be discovered

Why do we automatically know exactly where all resources are right from the start? Before I can even drill for oil, I know where it is.
Suggestion: Introduce some kind of search/prospecting/discovery of resources. Some are obvious and their surface layer would be known from the start. But something like a sonar/ground radar/test drill function/radar shack/pulse emitting vehicle/scanning vessel with randomized locations and/or quantities of subsurface resources would be an unknown from the start.