How Much Should I Tip After a Meal in Vietnam?
Tipping is not customary in Vietnam and will be met with confusion in most small family-run restaurants. You may still consider leaving a tip for exceptional service. More expensive restaurants that cater to visitors are accustomed to tipping and some will even add a service charge to bills.

It's more than just having a good time or visiting beautiful places (although that's absolutely a part of it!), it's about being part of a unique experience that stays with you.