That's a fair point.
A £50, 3-9x40 scope will be adequate for hunting rabbits with a 12ftlb airgun, although a more expensive scope will generally give better images (shaper image, more true colour, brighter, less image distortion), which is very helpful when hunting in mediocre light conditions, such as dawn/dusk/woodland.
I could get the job done with a Nikko Airking 3-9x42 and a HW95K. Total cost about £325
But I could use a Lightstream 4-14x44 and a HW100k (£1100) and have a much easier time and bigger "bags".