Being in retail....I take all discounts!!! I don't care if they ask and they are wrong, I don't qualify but if I did....I would be happy they asked & hey I got a discount I may not have been aware of (every store is different with their ages, etc...). I probably would have laughed because it is so darn hard to gauge ages! I am horrible at it (I always tend to guess in the WRONG direction -- making people older than they are!).
My guess is there is probably some matrix that the powers to be came up with that if you can't wait for them to ask for the discount, you must ask everyone (since it IS hard to guage ages, especially females with dying hair, etc...) & the managers sit behind you and WATCH to make sure you are actually asking the questions corporate tells you to.
Plus, you never know if it is a secret shopper, etc....