You're right if the land is sold at market price. If it's sold at a discount because of the restrictions, then continuing to enforce those restrictions is valid. The land's value is permanently reduced due to the inability to build, and the price reflects that.

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Dylan16807 2 hours ago | parent [-]

The price only reflects the future value out so far. The market price is based on a small number of decades. So for the purpose of respecting the discount, that reason dries up after a while.

	▲	_heimdall 2 hours ago \| parent \| next [-]
		Stipulating that such contract must expire after a period of time seems more reasonable than saying such a contract isn't valid at all.
	▲	triceratops an hour ago \| parent \| prev [-]
		So add a time-limit to the restriction.