Nothing related to capitalism or socialism here. Just 2 different systems in place.
US airlines have a separate F cabin with better seats. These seats are sold as F and the unsold seats (most of the seats on many flights ) are given as upgrades to elite pax. In Europe, C seats are the same as Y but they block the middle seat. So they can adjust the size of the C cabin on the basis of the actual bookings in C (by movng the curtan) and therefore there is no need for upgrade (or very limited).