Sugar... in Salt??

I was grocery shopping with my daughter not long ago...

She was hunting for salt - with no sugar (or dextrose) on the list of ingredients.

Really?! They put sugar in salt?! I had never noticed. I guess I assumed that a box of salt contains... just salt!

I don't add salt when I cook or bake, so our box of Sifto salt has been around for a while... No sugar listed in the ingredients - though it does contain more than salt!

I wonder why some salt has sugar in it...