Of course exchanges can be conducted to mutual advantage. People are better at some things than others. Taxing the transaction “income” makes it not an indirect tax.
Feel free to barter. In that case there is no money income, and no income tax. Historically Coins never had the full weight of metal in them. The difference between the face value and precious metal weight was a tax, but not a direct one.
And here I thought I was exchanging my labor for dollars. Hard to believe that is income, or gain. I guess I’ll avoid the indirect income tax by quitting my job.