@ghost_bird It's some (very effective) form of self-upsell: at each stage, that voice is encouraging that "well, if you did /this/ too, it wouldn't be much extra work at all".
See also: only wanting something simple with rice, and leaving with a jumbalaya of chicken, kielbasa, prawns, rice, chickpeas, celery, onion, mushroom, and tomato. (With thyme, sage, cayenne, Sriracha, garlic purée, and smoked hot paprika)