memes

Yes, but not guaranteed, and usually "somewhere else".
Instead of avoiding paying $50M in federal taxes like a lot of people think, they might be forgiven $1M in taxes at the local level, pending some sustained employment level for some duration or another.

Point being, they're usually not planning to do the charity to save tax money, but to gain goodwill. They definitely intend to use that goodwill to make or save money later, and a common way is "you want us in your community, don't tax us in buying the land 🥺".
They might also just use it for advertising so people forgive 5% higher prices.