Not clear if Tusk is acting as a carrier broker (i.e. retailer pays tusk who subcontract to regional carriers with Tusk providing pickup and onwards forwarding to a regional carrier hub) or just carrier management solution (selection of the right carrier–would need this capability as a broker)
Brokering is common for international parcel delivery (PitneyBowes, DPD, Asendia and others do this)
@Miles_Thomas in your two examples, Tusk is more of carrier broker (Shippers pay Tusk, Tusk pays Regionals + Tusk coordinates operations). We’re often listed as a carrier option within other Carrier Management Solutions (like Shipstation) or even WMS providers (like Deposco), so that a Shipper can select Tusk as an option when our prices are lower or speed is faster than their other carriers.