Yup, there are cheap salts with their own toxins and even expensive Himalaya salt can probably contain bad stuff. But at least here in germany, there are (non government) organisations that test food for their poisons and you can buy their test results, also for salt, in the shape of a magazine.

And even they can be wrong, sure, but I can still avoid poison where possible, so if I see no reason to voluntarily add cyanide on top of all the other shit for no good reason, I simply won't.