It's plausible that it's talking about electrical energy (Escalator, Lift etc) rather than physical. Though yeah I get where you're coming from, would bother me also.
Technically, yeah, 1 kilocalorie (kcal) = 1000 calories (cal), but in a lot of places (e.g. Americuh), we use the "Calorie" (with a capital C) in place of the kilocalorie.
This means even if you wanted to be environmentally conscious and take the stairs rather than using electrical energy to move the elevator, somewhere there is still energy being spent to create the food that's giving you that energy, and the electrical grid and elevator can do it at a way higher efficiency than you and the agricultural industry can, especially once multiple passengers are involved.
Kinda true, but not because of the formula. Elevators are really efficient now because of constant innovation. The actual dilemma is that you 'should' use elevators if they are already installed, but considering their construction they are way less energy efficient.
I suspect the actual energy cost of going up a few flights of stairs is entirely negligible compared to the subsequent reduction in energy usage for transportation of said human if their weight were reduced.