Indeed - there was functionality/a module in later versions of X-Cart 4 for this to make people agree to cookies before shopping.
However, by X-Cart 5, they correctly realised that this was overkill, and visitors just need to be made aware of the cookie policy, so no such popup or anything is required anymore - hence v5 not having anything.
https://kb.x-cart.com/look_and_feel/getting_compliant_with_the_eu_cookie_law.html
So the popup was a requirement, but not anymore.
Having failed to upset small businesses that way, next up is GDPR legislation - which should be getting more attention than it is.