In my experience, nearly all metal-detecting enthusiasts hope to find valuable antiques, not modern iron scrap. Alright, some of them hope to find lost jewelry, but also valuable antiques. None of the ones I've known are prospecting for boring metal veins, for example.
There is a bit of a line to be drawn between 'valuable antiques' and things that are 'archeological' though. Lots of people are happy to find bullets and belt buckles from 100 years ago vs specifically looking for iron age artifacts.
