A fork is a finished consumer product. Even if it's made of silver, you can use it to eat with.

Bullion isn't a finished consumer product, it's the packaging format for the raw material.

Sales tax applies to finished consumer products. The intermediary stages are traditionally exempt, i.e. the person who buys bullion in order to make silver forks doesn't pay sales tax, the person who buys the fork does.

Craft stores still add sales tax to raw material. Costco charges sales taxes to business accounts, unless given a certificate of resale or buying from an exempt category in whatever state. I could go on, but clearly sales taxes apply to more than "just" finished consumer products. They apply pretty broadly to retail sales as a whole.

It's at least a distinction though, unlike the other arguments.