The physical existence of a resource is separate from whether it is cost-effective to extract. Britain had not literally exhausted all of its coal and other reserves. Reaching and working many remaining deposits cost more than obtaining the same material elsewhere. Claims that a country has run out of a resource can therefore conceal an economic decision about depth, infrastructure, labor, and competing sources.
Notable Point · 1:31:47-1:32:35
Resource reserves are not the same as economical extraction
Britain still held large mineral reserves, but deposits could be too expensive to work when cheaper supplies were available elsewhere.