Development rights are made up by cities and don't have a fixed supply like land, so can't be taxed in the same way. For example, cities often grant development

Development rights are made up by cities and don't have a fixed supply like land, so can't be taxed in the same way. For example, cities often grant development rights over highways, creating them literally out of thin air. This gets even messier in cities like SF or Boston where the zoning rules are basically never followed and instead development rights are granted a on per-project basis, often based on how hard various groups lobby for or against a project. That makes a land tax not make any sense in large cities.