I'd say the writers of the article have an agenda: to get the "retentions" on exports removed, which is why they disingenuously lump together all exports, both finished products and raw agro materials.
Creating finished products (or, at least adding value to raw materials) creates employment, and both workers and companies pay taxes.
A hugely mechanized agro industry exporting grain does not create employment, and would, unless otherwise required, pay almost zero taxes, despite using huge amounts of land, and public goods such as roads and waterways.
There are very few countries that export agro raw materials at the scale Argentina does, so there's not much to compare with, but, for example, other raw material extraction and export industries, like mining, get to pay royalties. I have no idea what retentions would be "fair", but between 10 and 30% doesn't sound bad.