The oranges you buy in store are probably USDA Grade A, or some similar industry standard. In simple terms "nice looking oranges that arent misshapen". These are the best oranges picked so command the highest prices. The process to get to you also has the most waste - oranges that get damaged in transit, get damaged in the store, or don't sell by the time they get old. They're also the most expensive to handle - they need a lot of packaging and need to be cared for, and take up a lot of real estate in store, have short storage times at warehouses, etc etc. So they're the most expensive to buy from farmers and the most expensive to get into your shopping basket, so the sale price needs to account for all that.

Oranges that aren't pretty - too small, misshapen, not as nice a color, bruised, insect damaged, etc etc don't get sold fto retailers. Customers simply will not buy them and theyll rot on the shelves. They are a lower grade and are sold much more cheaply to food processing companies who don't care about any of that stuff as they're going to mulch thr oranges down into juice and jam and so on. So they're cheaper to start with. There's also less waste - if some get bruised - shove them in the juicer anyway. And once they're juiced their shelf life is better - so there's a lot more time to get them to market and they can sit in the store longer - unlike the orange bin in the produce aisle the retailer rarely has to chuck out a ton of juice each week because fickle customers won't buy it. All this and more translates to a much much cheaper orange by the time it gets into your shopping trolley