All foods must be burnt down to an ash in order to calculate how many calories they contain, in fact that's what calories mean, it's how much heat energy can be derived from burning them down. What you are calculating there is the same weight amount of meat burnt down from raw or from cooked. As others said, cooking reduces water weight (and some fat also), so if you take say 900 grams (2lb) of raw meat, and you cook it, depending on how rare you cook it and the cooking method, you may end up with 800 or 700 grams of cooked meat. So then when you enter 900 grams of cooked meat for the comparison, that's really a larger amount of raw meat they started up with, so it may be the equivalent of starting with 1000 or 1100 grams of raw meat.
If you take rice or other dry foods that add in water weight as they are cooked (because they're boiled or steamed and absorb water), you'll see the opposite effect. There, 900 grams of raw rice may equal 3500 grams of cooked rice or what have you, so you will see the cooked rice having much less calories, just because there's less rice and more water in the same weight of cooked rice versus raw rice.
Those options where you can calculate the nutritional value of raw versus cooked meats are not meant for people who eat raw meats, they're meant for people who want to know how much calories are in a particular amount of meat that they know how much it weighs raw, or if they know how much it weighs cooked. Most people just know how much it weighs raw because when they buy it, it's weighted in order to know how much it sells for, but they don't weigh it again after cooking, so they don't know how much it weighs then. Some people do weigh after cooking and for those they can check how much calories there are in a set weight amount of cooked meat.
There is an argument made by some such as archeologist Richard Wrangham, that our bodies derive more nutrition from cooked than from raw foods. I think he is completely wrong and even dishonest. But he claims raw foods, even meat, provide so little nutrition, that an averaged sized person would need to be chewing food 16hs a day to achieve caloric sustenance. But in any case that has nothing to do with the calculations you're seeing, as those calculations only consider how many calories are in each food, not how many are absorbed and used by our bodies or in what way they are used.