"...why isnt it obvious to the people who matter...?"

I would argue that it is not obvious.  There are only stringers or narrow veins on the surface, rich though they may be.  If there is an ore body, it is below 200-300 feet of marbleized capping, which means that compared to other types of mineral exploration, the next step - drilling - is a heck of a lot more expensive than the usual next steps, and by tens of millions of dollars.  Fewer investors are willing to take such a giant leap.  At this level, investors often have to answer to their boards of directors and other individual investors, meaning these are usually conservative people (in so far as one can say that about investors in mining).