1. Wheel cut salmon steaks have more spines and less meat, and are lower in fat content, which is less suitable for raw food.
2. The nutritional value of wheel cut salmon steaks is relatively not that high.
3. The brand of wheel cut salmon steak is not well known enough and needs to be sold at a lower price to make a name for itself.
Overall, wheel cut salmon steaks are cheaper partly because of their relatively high taste and nutritional value, and partly because the brand and the market need to gain more awareness and market share.