This heading exists for subjects that genuinely belong to no single place, and it carries a standing risk that the atlas states here rather than pretending away.
Some things really are cross-cultural. Every human society buries or burns its dead, marks the passage from child to adult, and has practices for illness and for weather. A page about death rites in general is a legitimate object, and comparing them is how anyone learns what is distinctive about any of them.
The risk is that a global heading becomes a place to put things whose home was never established. Several of the great comparative categories of the nineteenth and twentieth centuries turned out to be that: shamanism, totemism, animism and fetishism were coined by European observers, applied to societies across four continents, and treated as one phenomenon on the strength of surface resemblance. Every one of them has since been criticised for describing the observer's framework better than the practices. Shamanism is the clearest case, since the word belongs to one Siberian language family and was extended to unrelated traditions that had their own words.
The atlas keeps such categories because the literature uses them and a reader will search for them, and records where each came from and what it flattens. The working rule is that a tradition goes under the region it belongs to whenever one can be identified, and comes here only when the subject really is the comparison itself.