Why as the head of state does the queen give royal ascent to acts of parliament?
If you remember your history, the Civil War ended up with a royal, Charles I, losing his head. Parliament cemented it’s power, and successive royals have allowed the activities of Governments at their discretion, very rarely acting against them. When you say that the majority of the population disagrees with something, you have to back that up with a referendum or an election. As the Government is the elected representatives of the people, the Queen has to accept that the majority of the people have expressed agreement with the elected Members of Parliament. She therefore, has to accept, unless proven otherwise, that whatever Acts are presented to her for her royal assent, are the will of the people. The people she has dedicated her life to serving.