Actually the British system works pretty well for both the government and metal detectorists.
In many countries it is illegal to metal detect period. In England, they regulate it a bit allowing people to detect and keep what they find unless it is something of significant historic value. In that case the government buys the item(s) from the finder a negotiated fee in order to insure that the items stay in the country.
It's not a perfect system but I know many people who have detected in England and 99% of them like the system that is in place.
I was stationed on an old airfield in Germany that was the site for Rudolph Hess' take-off for England.
Brought my metal detector one day and went to a far side of the site and started detecting.
All I found were old pieces of scrap metal. :-)