Green shoulders

When tomatoes ripen and still have green shoulders, are the shoulders usually unripe, or are they like green-when-ripe tomatoes there?

I mean, is this usually uneven ripening, or are they usually bicolor (e.g. GWR and red)? I'm pretty sure I've seen some that had just ripened unevenly, but I'm not sure that it's the norm. (After all, some tomatoes have yellow shoulders, but the rest of the fruit never turns yellow at any point.)