There'll definitely be people in that camp, with good reasons for holding on to land. Flipside, there are many other people that know the land value mechanic and take advantage.

A transfer tax is decent, but it can be sidestepped by just holding land and selling when the tax changes. Land holding is a long game.

On the other hand you could argue that someone who had a better strategy for accruing capital should instead have purchased that land. The opportunity cost of nothing happing on that land is there regardless of the users intended future development.