Another potential reason it was never scaled up to carts is they didn't have access to a great draft animal candidate. Without that early carts are a lot less u

Another potential reason it was never scaled up to carts is they didn't have access to a great draft animal candidate. Without that early carts are a lot less useful. The largest options were llamas or alpacas which are still fairly small and weak as draft animals go. The nearest option would have been buffalo in North America but they don't have great base temperaments for domesticating and they're not geographically relevant to South America even if they were.