I deal with lots of rural property in an area that is quickly changing to residential. I just showed a 13 acre beautiful property that was zoned residential with $8500 per year taxes. The owner claimed it could be zoned for horses just by putting horses on the property. That is not the case. The zoning department is not necessarily the friend of land owners and more likely friends with the tax assessor.
The zoning department was originally created to protect unknowing potential buyers from unscrupulous builders and developers. They established minimums and maximums for such things as setbacks, building size, usage of the property and safety for the general public.
Today to change a property from one zoning to another you can look at the tax basis to ascertain how a property is likely to be zoned. The higher the tax rate the easier to get zoning changed to that higher rate. It is fairly difficult to get zoning down zoned hence from business to residential or in our case residential back to agricultural. These are questions that you should ask your realtor and possibly need to retain an attorney to straighten out before closing on properties today.