I also have a terrible palate, do you think that's part of it for us? Beef is a fairly "guaranteed" taste that, depending on the cut, will give you what you're looking for regardless, I'd expect.
What do you eat besides meat? Since meat has the lowest energy density, you most likely get your energy from other sources anyway. Even if you eat 500g / 1lb per day for a 2000kcal target, you would still get 1500kcal from other food.
Average red meats will have calorie ranges right around 180-240 kcal per 100 grams. Of course that's low compared to sugary processed foods if you're going just by calories.
But it certainly isn't lowest when you consider the entire food pyramid. (most veggies and some fruits are lower)
Yes, I was thinking in the way of radicalbyte's comment and I take the dry values of carb sources which indeed reverses the ranking.
But even with beef, it takes 800g to reach 2000kcal[1]. I am just wondering if this can actually be the main source of energy for a long period of time.