This move was as controversial as it was unprecedented. To some, it's a way to show Saudi Arabia's ambitious plan to create technologically advanced cities. To others, like a group of Twitter users who created the hashtag "Sophia calls for dropping guardianship," it's hypocritical. Saudi Arabia is known for discriminating against women and migrants.
Sophia is designed to look like Audrey Hepburn, and Hanson Robotics describes the robot with female pronouns. Critics therefore found it especially odd that Sophia received citizenship while breaking commonly followed rules of Saudi Arabia's guardianship system, which applies to women in the country. Sophia not only addressed the crowd without wearing a head covering, but also appeared without a male guardian.
Sophia also got citizenship on its first visit, while many migrant workers are stuck stateless in Saudi Arabia because of its kafala system. This allows governments to "sponsor" migrant workers to come work in the country, but it also forces workers to obtain permission to leave the country.