I don't think the US has strict regulations on the ingredients... I don't know why, likely lobbyist behavior, but also I think people just accept that if you smoke you don't give a shit and it's unhealthy by default, so it's not a big deal if they add chemicals.

Which becomes more ridiculous with nicotine pouches for this reason. Nicotine isn't cancerous, so it would be super shitty to add carcinogens in the pouches and then claim it's a tobacco product so you should expect it.