I don't see how being forbidden to eat something because of your religion could be classed as fussy.
As for vegetarians and vegans; for most I'd say it's an ethical choice and thus not fussy. For others, certainly a few I've met, they don't like the taste of meat. Not liking the taste of...
My brother and I used to be really fussy.
Mum would have to cook two different meals; one for her and Dad and then one for me and him.
We've mostly grown out of it but there's still foods I'm not overly keen on.