I had a chance to see how an ad is being served without link extensions when the maximum bid is for example $0.85 but they show up if the bid is $0.95 The ad would maintain positions 1 or 2 (more the second one), but extensions would show up only if the max bid is at certain level.
Since the ad is getting to the position given anyway, why higher bid for link extensions to show up?
I may have a similar case when an ad is the only one showing in the space, but the bid level determines if the ad will be shown in the premium yellow area on the top vs. yellow area on the bottom. Can't compare it directly to the case above, but wanted to mention it as from time to time I come across situations where the system requires higher bid while that does not seem to be needed.
If I had a car tuned to work like AdWords, the car would be running and making some gasoline for sale, I guess.