American who sometimes travels out of country here. I don't feel right *not* tipping after someone performs a service - even though I know they're getting paid. I've learned that I can tip - so long as I apologize profusely about doing it "very sorry, my mum taught me to do this as a way of saying thank you - and your service was very good". In Auckland, I found myself justifying a tip to an Uber driver by listing all the "beyond standard service" things he'd done for me.