I used to work in film, although not in the accountancy/deal-making aspect. Film tax breaks are direct discounts on money spent. If you make a film in Georgia, for example, you get a transferable tax credit (20-30%) on money spent in the state. It's a short term deal (productions usually only last a few months), and is immediate in effect. There's no "spend a billion of public money and maybe we'll hire some people" shenanigans like the Foxconn plant in Wisconsin.