Why would you want a solution that makes one family be treated as if they're above everyone else by birth? Is that the signal that as a country you want to give

Why would you want a solution that makes one family be treated as if they're above everyone else by birth? Is that the signal that as a country you want to give your citizens? I cannot understand how people consent to monarchies in so called developed countries while at the same time making huge fusses about everything else related to equality.