I was confused as well, which is pretty bad considering I have two kids there. In general, I have found (at least for both of mine over the past 2 years) that they rarely eat 3 meals a day and often might just have an apple and coffee or something not even worth using a meal for (instead they use the bonus bucks). Also, there are several off-campus places they can (and will) use their Carolina card - for example, my daughter goes to Moe’s at least 2-3 times/week, considering it’s right next to her dorm! - But those off campus places do not count towards the allotted meals either.
And as scmom12 said, you can always increase your meal plan but cannot decrease it so it’s better to start off smaller. That said, I just signed both up for the “Carolina 10 Platinum” which gives them 10 meals per week plus $325 bonus bucks. I feel like that will suffice but if not, I can always increase it- or just add money to their accounts, which is sometimes less expensive too.