Tips by definition is optional, and it should not be a "must".
If the service provider feels she requires a tip than, she can raised the price or tell the customer her total cost is the price plus "xx%" tips.
fyi, I do give tips if I received great services, but not often...
Asian views tips differently, especially in Japan.
Tips is kind of North American culture, especially engaged with hand-on services.
Even my children pay tips to:
Hotel room-service, restaurant, taxi, hair-cut etc.