The back of a package of Upton’s chorizo seitan says “vegan & plant-based”. I’ve talked with a couple people about this before: plant-based isn’t inherently vegan, but there are only a very select few implausible ways to get food that’s (varying degrees of debatably) vegan and not plant-based. We’re talking, like, accidental roadkill, a hamburger you found in the trash, an animal killed in a dire survival situation… (Edit: Okay, I guess pure salt as a meal also applies.)
So Upton’s, I’m really glad you reassured me that it’s both.
It’s not really a USA thing as such, it’s because cane sugar is more common in the US while e.g. Europe primarily uses beet sugar. Beet sugar is lighter and needs less refining to make it white, so bone char is basically never used for beet sugar. The same applies to Agave too. And to HFCS.
For liquid sugar it depends on what sugar it was made from, it can be made from cane sugar but also from beet sugar.
Organic sugar doesn’t use bone char in the US because USDA doesn’t allow animal derived processing aids for organic products.