Is it illegal to rob a wedding car for sugar and cigarettes?

Your question is quite interesting. The key lies in the word "robbery".

Those who "rob" seize, intimidate and coerce. Not only breaking the law, but if you have a weapon, you commit a crime directly.

Since it is a legal issue, we should talk about it.

According to the nature of your question, or to put it another way, change "robbing the wedding car" to "intercepting the wedding car"?

If you want sugar or cigarettes, you have to have a degree. It's like making a wedding. As long as the other party can accept it, it's not illegal.