What you're describing sounds like what we call "in current use" in New Hampshire. I know Maine has something similar but I can't remember what they call it.

You don't pay taxes on land in current use, but, if you or whomever you sold the land to, wants to build on it, they have to pay the back taxes first. It's a great for conservation.

seems like this behavior would have a chilling effect on deathbed donations, especially when it sends the message gives: "screw you, we'll do what we want"

I also don't see how this behavior is in the public good, even if the donor has some ulterior motive, governments are free to reject donations

Yeah at that point it should be in a perpetual trust or some other holding co who can fend off the city. Never trust your neighbors with your stuff.

This one leads to some very odd lawsuits.

https://www.washingtonpost.com/nation/2024/06/24/corner-cros...

The law addressed this centuries ago. The general rule is that you can enforce such rules for a generation plus twenty years. That may seem like a long time, but the rule prevents the "cold hand from the grave" dictating how living people should act.

https://en.wikipedia.org/wiki/Rule_against_perpetuities

In this case, the farmer should have talked to a lawyer first. There are ways to set thing up to prevent misuse.

>There is a tax loophole where you buy a lot of land and donate 90% of it to the government to be "public parkland". However, in actuality, you're the only person who has convenient access to this land

While I'm sure that's happened once or twice and serves as great fodder to get people of a certain ideological bent riled up, for the most part nobody is giving government land that's worth a shit. They're doing it to land that's effectively unusable due to regulation. Like if you own a strip that's a many acre 30ft wide along a steep river bank plus some space for a house (the lot layout could be the result of an old railroad or industrial thing) you gain literally nothing being on the hook for all that and you can't use it. That sort of thing is the typical case in which these sorts of things are invoked. It's more of a "well if you jerks care so much about what I do with it you can have it" type deal than a tax dodge.

Public parks should not be developed on for the sake of the community. We need wild areas.

> I don't think you should be able to block development on land you donated indefinitely.

On land you contractually purchased with the condition that development be blocked indefinitely? Then why sign the contract? If they wanted a time limit, they could have put it in the contract, or not signed the contract.