Of course it's more affordable. Is it surprising that lower quality, factory farmed food is less expensive than higher quality food?
If you made lower quality food (e.g. fast food, processed foods, TV dinners) more expensive through regulation and taxation, you wouldn't magically lower the price of higher quality food. The higher quality food would still cost as much as it did before! All that you would do is make it less affordable for people to eat as much as they want to.
And how do you think this could film could be paid for by McDonald's or other food manufacturers? Hello, do you look at what fast food joints sell? Sugary drinks, french fries with ketchup, sundaes, ice cream cones, mcflurries and God knows what else. This documentary film is highly critical of such foods.
The point of the film is this: You crave sugar, salt, and fat, because in nature foods that have sugar, salt, and fat are healthy. You get the sugar from fruits and the fat and salt from wild animals. The fruits are high in dietary fiber and antioxidants while the wild animals are high in omega 3s, vitamins, and minerals.
But modern technology has allowed us to hack our cravings, so now we have foods that have the sugar, salt, and fat but are devoid of the nutrients found in sugary, salty, and fatty foods that are found in nature. For example, sundaes. Or factory farmed meat which has a pathetic fatty acid profile when compared to game-meat.
And the fact that people buy this crap isn't the fault of business, it's the fault of people who demand this kind of food. Business simply fills demand. If people wanted to buy more grassfed beef and fruits and vegetables, you can bet that businesses would drop the unhealthy foods in favor of these healthy foods.
BTW, Penn and Teller made a good episode on fast food as well:
YouTube - Penn and Teller - Bullshit S08E02 Fast Food Part(1/2) and
YouTube - Penn and Teller - Bullshit S08E02 Fast Food Part(2/2)