Why? I am not saying the American market would provide Americans with pork that's safe to eat raw.

That's because Americans don't typically eat their pork raw, so they don't care enough for the market to supply this product.

Even then, raw pork requires 100% carcass inspections or sashimi-like freezing to reliably prevent the parasite infections.

Because if the market had been providing them what they did want (clean meat of any kind) that act wouldn’t exist. Prior to that act the American people thought they were getting a clean product, a few journalists and a government investigation later it was concluded broadly that the meat packing industry was failing.

The Jungle by Upton Sinclair ended up being a major catalyst, there were a lot of claims by the meat industry that the book’s account was overblown, but as evidence piled up regulation was demanded.

Markets only work when everyone is forced to be on a level playing field. Sometimes you need regulation to provide some minimum proof of this, sometimes market players themselves find it desirable even, otherwise new market entrants can make a much much lower cost product that relies on market ignorance of what people are buying (so what if all the meat is packed by people on their death bed and sick… my margins are better).