To quote Wikipedia (I know quoting it is not the best thing to do HAHA, but still it can be a good source of general information) but anyways:
But the cat at the canteen today simply did not catch the rat- in fact, it thought of it more as a toy or something, chasing it around the canteen. It was more like curiosity rather than it actually 'hunting'. Perhaps you could say that the cat was not very hungry but I doubt it had eaten much, since it's the term break & probably no one came to feed it. The cat continued to follow the rat. In the end, the cat did not catch the rat and watched it scurry away.
Even well-fed domestic cats may hunt and kill, mainly catching small mammals, but also birds, amphibians, reptiles, fish and invertebrates. Hunting by domestic cats may be contributing to the decline in the numbers of birds in urban areas, although the importance of this effect remains controversial. In the wild, the introduction of feral cats during human settlement can threaten native species with extinction. In many cases controlling or eliminating the populations of non-native cats can produce a rapid recovery in native animals. However, the ecological role of introduced cats can be more complicated: for example, cats can control the numbers of rats, which also prey on birds' eggs and young, so in some cases eliminating a cat population can
actually accelerate the decline of an endangered bird species in the presence of a mesopredator, controlled by cats.
Maybe cats no longer actually catch rats/insects/etc, or hardly ever. Haha does this discount them as 'useful pets'? Hehe... Perhaps this is also due to human intervention; the cats no longer 'hunt' because they're fed by cat-lovers???
Just an assumption and food for thought! ^^"