1. Temp: No backup, cleared regularly
2. Cache: No backup, cleared when space is tight
3. Local: Local backup only, never cleared
4. Documents: Local/cloud backup, never cleared
5. Cloud: Cloud backup, cleared when space is tight
The problem seems to be that #3 doesn't exist. Yet you'd think it would be a common requirement for stuff like in-app purchases of large and essential content packs, for example, turn-by-turn navigation maps.
I'd hate to be on holiday and have a 10 megabyte podcast download automatically trigger the erasure of 1000 megabytes of navigation data.