With Superior or other satelitte/video auctions you need to have enough calves of similar weight, sex and age to make at least a half a truckload. You could sell a half a truckload of steers and half a truckload of heifers to make a truckload. A truckload is 48,000 to 50,000 lbs (80 hd of 600 lb calves would make a truckload).
The local sale gives you a place to market less than truckload lots and cattle with too much weight and age variance to suit most buyers.