Taxes/fees/whatever are taken out when money changes hands. Whether it moves from one individual to another, or between an individual and a company, or between two companies, etc. It doesn't matter. It's just "single" taxation. But there might be a series of them with N hops.
Consider this: consumer A pays out money to buy some good from company B. Out of that money, some is siphoned off in the form of sales taxes. The company gets the balance of that. Company pays some portion of their earnings in taxes. Company also pays some portion of their revenue to their employees. Out of the money paid by the company to their employee, some is taken out as tax. Employee gets the money. Out of that money, he uses some of it to buy some product. Out of that total purchase price he pays, some is taken out in sales taxes. And so on, and so on. Repeat with other sorts of transactions and money flows. Thus, there is no "double taxation" just taxation. If you argue there is double taxation, then, in reality, there is also triple taxation and quadruple taxation and infinity taxation.
Double taxation is code for "I just don't like that particular tax and want it reduced or eliminated". It is not a factually valid criticism in and of itself, by my reasoning.