Why Nasa chose SpaceX over Boeing to bring astronauts back to Earth?

Two US astronauts, Barry Wilmore and Sunita Williams, who arrived at the ISS on Boeing’s Starliner, will remain for six more months due to thruster malfunctions. They will return on a Boeing’s rival SpaceX vehicle instead. Nasa emphasised safety as the reason for this change. The Starliner will return uncrewed in early September, providing more data for future missions.