Why do spices need a hechsher?🧂

Okay. Why do spices need a hechsher? Once you've got a blend, which most seasonings are  a blend, so then it needs a hechsher because it   has all kinds of additives that are put in there  to help keep it together or separate depending on   what they want. And you have equipment, shared  equipment with beef and chicken. So that's   why a blend certainly needs a certification.  Straight spices sometimes do, sometimes don't.