Perhaps Birkenstock-only stores have a contract with Birkenstock that defines transfer of product from Birkenstock to the store as not a sale. Could be a consig

Perhaps Birkenstock-only stores have a contract with Birkenstock that defines transfer of product from Birkenstock to the store as not a sale. Could be a consignment. Then the first sale would be to a retail customer (or to Amazon, in the case discussed here).