I've only had 1 experience with a caddy, and it was the strangest experience ever. I was in Malaysia and both carts and a caddy were mandatory on weekends!! LOL
I played 4 rounds.....two as a single during the week, and 2 as part of a 3some on the weekend.
We had a weekend 3some riding 2 carts on the weekend, and 1 caddy. The caddy would jump on the back of a cart and ride along. He had no purpose except for entertainment. He'd pick fruit from the trees and try to give us a local education/taste testing on vegetation along the way. I don't even remember him giving us yardages.....my only memory of him was him picking fruit!! I honestly don't remember how much we tipped, but it was probably equal to 1 weeks wages for the average Malaysian laborer.