Voting is a more fundamental right than going to a restaurant, because if you can vote then you can potentially change the laws about requiring an ID to visit a restaurant.

Also, there probably aren't many attempts to prevent 5 year olds from getting IDs, since the people in charge of issuing those IDs don't need to worry about 5 year olds voting them out.

And 4 year olds will need to show their birth certificate in order to prove they are not in violation of a vaccine requirement.