Pricing model is difficult and a multifaceted puzzle. In seasonal operations prices are always higher as the revenue must cover the capital costs of the down time of the off season. Building, maintenance, and equipment costs continue year round. Revenues must cover those costs year round as well.
That said, quality of the experience should be a fair value. Whilst on-park the dining experience is effected by the overall ambiance of the park, specific sub themed area, restaurant design and service style, and of course, cuisine offering. A variety of offerings enhance the overall experience. Having stand-out offerings go quite a way toward enlivening the park and the total guest experience.
Examples abound. Who would think of going to Knott's Berry Farm and skipping the chicken? Or how Kennywood has elevated the lowly French Fry to a dish worthy of the cuisine label? Pinks at Cedar Point has done the same--making it not just another hot dog. The fresh baked cinnamon bread at the mill at Dollywood is worth the trip.
Pricing is a sticky wicket. The price must be adequate to cover the added costs of seasonal operations. Captive audience pricing also commands a premium.
To address Shark6495's question, the park would make more money selling the $12 dollar combo over doubling business with two $6 meals. The math makes it simple: two meals revenue $12 minus food cost for two meals would leave less revenue to cover all other costs--known as the "contribution margin"--than one twelve dollar meal minus the food cost of one meal. Thus the park would make more on the $12 meal. The real question becomes the caring capacity of the specific location and if that capacity is adequately being utilized. If utilization is sub par, due primarily to price, revenues and profit can be increased by adjusting price to generate additional sales.
Simply lowering prices will not necessarily make more money. Increasing quality and the overall experience for the money is often the better tactic. That drops more dollars to the bottom line.