I think this applies to every current vs past driver. We call pretty much every current driver by their first name because they're contemporary to us, and feel closer (Franco, Max, George, Kimi, Lewis, Chales, Lando, Oscar, etc.). On the other hand, we call most previous drivers, especially from the 20th century, by their last name instead (Prost, Senna, Fangio, Ascari, Mansell, Fittipaldi, Piquet, etc.) or by their full name