Newspaper Coupons and Discounts

Please tell me the rationale of putting product coupons in newspapers that insist on giving away:
1. A free box of biscuits
2. 10HKD off without condition (e.g. buy 20HKD worth or more and deduct 10HKD with this coupon) on Mcdonalds
3. 10 HKD off on Park N Shop (big supermarket chain here in hk) also without condition

That was the coupon for last Saturday, and since my parents were here and had nothing better to do, they prepped up the previous day, got up early on Saturday and bought 8 copies of the same newspaper just to avail of the discount.

I don't get how the newpaper or the advertiser will benefit?

At least 200 people lined up in front of Watsons to get the free box of biscuits.

How strange.