Why does cache use Most Recently Used (MRU) algorithm as evict policy?

Imagine you were looking up the details of buses as they arrived at a bus stop, based on their bus number (or whatever identifier you use).

It's somewhat reasonable to think that if you've just seen a number 36 bus, you're less likely to see another one imminently than to see one of the other buses that stops there.

Just one example, but the idea is more general: in some cases, having "just seen something" is a good indicator that you're unlikely to see the same thing again soon.

Perhaps a more tangible example would be a media server. When the user has completed watching a video (let's say it's an episode of a TV show), they are presumably the least likely to want to view it again. So if you must evict something, evict the most recently viewed item.

In practice though, I believe this type of cache is typically used in addition to an LRU or LFU cache, where the two caches in tandem allow you to cover a wide variety of cases.