Japan forces this to be the case with extremely high tariffs on rice imports. It's not that they won't consider it, they literally can't.
I see cal-rose for shy above 3000 yen. While I didn't grasp the details, I saw a news report which made it seems they've set up a quota (xx tons or something) of rice to be imported with almost no tariffs.
I'm not sure tarrifs have a huge impact; Japan is Australia's largest buyer of rice, importing $63.8MUSD worth in 2023 per the OEC: https://oec.world/en/profile/bilateral-product/rice/reporter.... That's a lot of rice to buy, if it's more expensive and less desirable then domestic rice.