The basic idea behind these things is as follows: the government passes some new regulation that restricts land use; a landowner thereby loses some of the value of his land (e.g., he can no longer sell it to a strip mall developer); the government is obligated to compensate that owner for the lost value. Only fair, right?
Put aside the practical consequences for a moment. Instead, answer me this:
The government frequently does things that increase the value of land. Hell, House Majority Leader Denny Hastert wedged a single earmark in a highway bill that netted him a 500% profit on a piece of land (he got a highway built next to it). The government builds highways and other infrastructure, for one thing. But more to the point here: If a government passes a land-use regulation preventing, say, strip club development on land adjacent to a residential area, the value of that residential area rises. The guaranteed absence of a strip club boosts residential property value.
Virtually every action government takes increases the value of some private property and decreases the value of other private property.
Why, according to the takings people, does government have to compensate for the latter but not collect for the former? Do they have any rationale for this?