APM gets inflated by counting several single actions as multiple separate actions. For example a Zerg player may want to turn larva into 30 Zerglings, they do this by pressing one button and holding it down as the UI repeats a separate action for each larva transformed.

By comparison selecting a single stalker, and having it jump to a new location is much more effort, but counts as fewer actions.

A thread from a few years back about TLO’s APM: https://www.reddit.com/r/starcraft/comments/4pnbv8/tlo_somet...