In a recent comment to this blog the writer says:
"Many collectors oppose the MOU because they feel not having them will somehow incent governments to adopt private property rights for antiquities found on private land."
You can't force a foreign government to change their laws to they way you think they should be. They enact the laws that they feel are in the best interest of their people, and that includes the protection of their cultural heritage. There are even laws right here in the US that will supercede "private property rights". For example, you can't hunt animals out of season, even on your own private property. Each community also has zoning laws that say what people can and cannot build or keep on their private property, and where. Those same zoning laws also say what I can use my property for (residential vs. commercial). Here in the US the government can even take your land from you if they consider it to be for the greater good of the public. You are paid what they consider fair compensation. Not so different from both Greek and Italian laws, where any antiquities found on your "private property" become property of the state, but the finder and/or owner of the property is compensated.
These laws are not so different from the "draconian laws" of other countries. You can own property in both Italy and Greece, just as you can in the US, but in certain instances, like here in the US, the government can tell you what you can and can't do with that property.
Greek law says:
Any person who finds or acquires possession of a movable ancient monument dating up to 1453 shall declare it without undue delay to the nearest archaeological, police or port authority and shall make it available to them. (2002 PACH, Art. 24 (1)) When possession of the antiquity passes to the State, reward shall be paid to the person who made the declaration in accordance with paragraph 1 [of this law]. (2002 PACH, Art. 24 (3))
By a decision of the Minister of Culture, following an opinion by the Council, a permit for possession of an ancient movable monument, the ownership of which belongs to the State, may be granted to a natural or legal person. (2002 PACH, Art. 23 (1))
In addition, Chapter 6 Art. 90 and 91 of Italian law also says that finders must report any finds, and they are paid a reward by the state, and reimbursed for any cost incurred for custody and removal should removal be necessary to ensure the safety of the item.
For links to these laws see here
The writer in the comment in questions also says that "Citizens need to be enticed to stand up to diggers and private ownership is the only proven enticement." Unfortunately, that's not true. Private landowners routinely allow diggers on their property, generally under the agreement to split the proceeds of whatever is found. In cases where the landowner refuses permission, digging often takes place anyway, this is known as "nighthawking".
There is a company in Texas that calls itself the "Texas Amateur Archaeological Association" that actively entices landowners to allow diggers on their land for a fee so they can "find their find of a lifetime". (Sometimes the digging is even done with a backhoe!!) How does private property rights help to deter diggers or protect historical sites?
The Grosby Garret helmet is a perfect case in point. If it was found where stated (and that is up for debate), it was found on private property with the permission of the landowner. The helmet was a rare specimen never found before in that area. The law allowed for it to put put up for sale as quickly as possible, but what could have been learned by further study of both the item and it's "find spot"? For one thing it could have put to rest one way or the other about whether or not that was the true findspot. No study was done. How did private property rights protect this artifact?
Not everyone is falling for the "private property rights" argument. Right now in Egypt there is a group that had filed a complaint with the attorney general and is calling for the cancellation of a television program after the preacher on that program issued a fatwa (religious edict) referring to the sale of antiquities saying that “If it is found on land that you own, or in your house, then it is yours by right and you are not doing anything wrong.” Not only is this contrary to Egyptian law, they argue that the fatwa poses a serious threat to Egyptian history and its national heritage. They consider the ruling as an affirmation of the looting and theft of Egyptian antiquities which are by extension, a part of the world’s heritage.
I agree that in most instances private property rights are a good thing, but in the case of cultural property the idea that "it's mine, I found it on my property, I can do whatever I want with it" is a very shortsighted and selfish position. Cultural remains, even those found on private land, can teach us more about the ancient civilizations that lived in those areas, and that benefits society as a whole. Just because something is found on private property doen't mean it shouldn't be recorded and studied before it is hastily put up for sale.