"Air Stairs" are expensive "options" usually exercised by ultra-wealthy, aka "Very Very Important Person" (VVIP) owners of Boeing Business Jets (BBJ) and Airbus Corporate Jets (ACJ). Flight Managers would rather not coordinate with airport management to bring mobile stair-trucks out to the aircraft, so it affords the crew flexibility to drop the principal off wherever they can park and have the limo door open once the stairs are down. One thing I learned working on aircraft of billionaires over many years is that their time is their most precious commodity in life. They never waste a second and employ "minders" to prevent them from doing so.