Because all the BS rent seeking parties you have to deal with as part of international shipping will make that $6k excavator 12-15k. A lot of costs are fixed per shipment hence buying container fulls and reselling.
And the Alibaba importer is going to care a lot more about satisfying a potentially repeat $100k importer over a one time $5k buyer, and when you purchase large orders like this you can set quality standards for your products and the seller is on the hook if the products do not match the listed requirements.
Basically, you're paying more but they're taking all of the hassle and worry and a large part of the risk out of the operation for their cut and you're not paying much more than you otherwise would for the service.
Basically, you're paying more but they're taking all of the hassle and worry and a large part of the risk out of the operation for their cut and you're not paying much more than you otherwise would for the service.