Both the president and Laura really respect the office of president. They are extremely classy people and being representatives of the highest office determines how they respond daily.
Laura Bush IS the quintessential First Lady.
Sorry. it has nothing to do with the office of president and first lady. It has everything to do with moral centeredness, humility, and gratitude. Mr. & Mrs. Bush would be like they are if they were your next door neighbors. It is part of their makeup, their wiring. It has nothing to do with their station in life.