Why are Russian dog commands like “сидеть” in the infinitive?

Russian dog commands are plain infinitives: сидеть! (“to sit!”), лежать! (“to lie down!”), стоять! (“to stand!”). The infinitive turns an order into a flat, impersonal rule, so it sounds strict and military. That’s why it works on dogs and in army drills, and why saying сидеть! to a person sounds rude or comic.

With people you use the imperative instead: сиди, садись, or polite садитесь, пожалуйста. Signs use the same infinitive trick: не курить (“no smoking”), не трогать (“don’t touch”). The owner here mixes both: Бруно, лежать!, then, out of patience, ложись, когда я тебя прошу!