Who is in the right in the Reservoir Dogs scene about tipping?

[7,052,770]

When I was in college, I made a point to tip exactly 15% of the pre-tax amount.

Then I realized I was being an ass, and now I tip 20% or more (and minimum of $2 for cheap meals), since waiters and they people they're forced to share their tips with are a lot more likely to be struggling from paycheck to paycheck and I shouldn't be begrudging an extra dollar or whatever.

Even if the service is bad, I don't feel right begrudging because I don't know everything going on in their life.

[Middle-aged Europe]

I usually tip the amount that is commonly used in Germany: 5%-10%. Most of the time it's closer to 10%.

[Alcibiades]

I generally tip 10-12.5%, which is the UK standard. Servers here have to be paid at least the minimum wage. This is often also automatically added as a service charge to the bill.

[Del Tachi]

Even if the service is bad, I don't feel right begrudging because I don't know everything going on in their life.

People shouldn't bring their personal life to work.  We expect this from professionals, we should expect it from service staff as well.

If the service is bad, I'll leave a bad tip and let the management know (if I think its worth it.)