You may want to look into what is happening in Toronto.
There are "builders" that "buy up" a handful of houses. Neighbourhood zoned where as-of-right is four floors. They apply for 30 plus floors, knowing they won't get it but it causes neighbourhood flight (people see the zoning application sign for 30 floors and freak out) allowing them to buy up more houses for even cheaper, well below previous market value, more zoning signs and failed zoning applications, boarded up houses and urban decay is the name of the game at this point. They still get rejected, rinse and repeat, hoard for up to a decade (five to seven years seems to the the sweet spot) until they sell to a real builder for a huge profit or possibly build something reasonable themselves (say six floors). This is actually quite common these days. One kicker, they don't even own the houses when they first apply as they apply before they close (homeowners are listed as the property owners on the zoning application, check it out, closing is years out). Some of these guys have displaced more people than they have built units, yet have dozens of zoning applications with the city on the go right now. There is one on a side street off of Westen applying for a 48 story building on basically a handful of boarded up houses, oh and the building they are applying for will only have five parking spots--complete nonsense but there are some hold out houses on the street they still need to squeeze out. If you follow them many never even schedule the required public meeting as they have no intention of building, just creating flight, buying up land driving down property values....
There was one near us that included city owned land in their application...but they never even approached the city to buy the land! Guaranteed fail, but I believe that was the idea. This one has been on the go since 2016!
Other better builders apply for reasonable zoning changes or better yet, buy and build to zoning. But even these guys have dozens of applications with the city but are not building much these days. Still some bad acting, they build less then they buy and have years and years of hoarded property in the hopper.
Screw carrots, we want housing we need to use a big stick to stop the land hoarding. Vacant hoarded land does not house people.
IMO, charge property tax on the finished building they are applying for after a grace period. Limit the number of applications they can make, raise that limitation based on what they actually build. Punish the bad actors severely, the rewards for the good ones, they build and sell housing and make money. Take the worst ones out of the equation, eventually there will be more for the not bad ones.
