re: Oprah advises tipping 10%???????? WTF?????

Without tipping for a service such as this, you provide no incentive for someone to perform their job better. By just providing a flat rate for some smuck to run your food too you, you end up with worse service than we already have now at many places.
You want to see your cost of a meal sky rocket, just ask a restaurant owner to start having to pay his servers $10 to $15 an hour.

Note: Most of what I wrote applies to nicer places. At your cheesy low end joints probably wouldn't matter if you have $8/hour Frank with no benefits running your food. Service already isn't all that great.