Why loose supply caches fail between planets

Could interplanetary colonization use desert-crossing-style supply drops along the route?

Not safely as loose caches; inhabited lunar interchange stations would be easier to locate, maintain, resupply, and use for transfers.

Interplanetary colonization is treated as closer to steam-era logistics than sail-era freedom of movement. Unattended caches would be difficult to keep on a useful route and could become dangerous debris as they accumulated material. Inhabited lunar and Martian-moon stations could handle transfers, repair, oxygen, fuel, manufacturing, and asteroid-resource processing. Those stations would need supply and investment of their own, introducing the commercial logic that would shape the route architecture.