Zoning is a promise from the government 'invest in a house (which is most people's largest investment in life) here and we guaranty we will work on our side to

Zoning is a promise from the government 'invest in a house (which is most people's largest investment in life) here and we guaranty we will work on our side to make sure it is fit for purpose (a good place to live/you won't lose money).'. These private property owners you are concerned about normally bought the land with these difficulties you are worried about priced in to the land's value. Why should to government hand them free money in the form of not enforcing what has been priced into the land value?