The true cost of plastic is cheaper by far than aluminum or other alternatives. Injection molding and other plastic technologies are miraculously productive and energy efficient compared to many other forms of production.

The U.S. produces 12,000,000 barrels of oil per day. 4,380,000 barrels per year. According to https://cleantechnica.com/2017/10/14/u-s-tax-code-4-6-billio..., we also subsidise this production by $4B per year, or about a dollar a barrel.

If you are saying that a $1 per barrel subsidy for oil causes the cost of plastic widgets to shrink appreciably, I think you are very wrong.

If you are saying that the total cost of the Iraq war should be rolled into the cost of plastic widgets, I think you are very wrong.