A product is worth more than the sum of its parts. More than just the labour and materials that went into it.
Economic rent is the difference between what a producer would accept for a product (because it covers the costs of labour and material) and the price the product can be sold for. Various factions involved in the production are in competition for a slice of these rents. The workers would like to have it as an increase in the price of their labour. The owner would like it as an increase in profits of the company. Both can claim a right to a larger share in that it correctly values their contribution.
In a complex SupplyChain a larger slice of the rent is usually taken by those closest to the customer. (DownstreamCredit).