Is more cooperation in the field of space exploration possible to spend less?

When we can read that “the United States is the largest player in terms of space spending, capabilities and assets in orbit. The government alone spends about $40 billion each year on space activities through the Department of Defense and NASA, with China and Russia next, at about $6 billion each. Japan, France, Germany, Italy, India, Canada and the United Kingdom together spend around $11 billion. As of 1 January, there were 1,459 satellites in orbit, of which 593 belong to the United States, 135 to Russia and 192 to China” (Nature.com); we can wonder why only the European nations have decided to come together in the field of space exploration to share resources to have better funded programmes? Indeed, when we consider that the Moon is declared to be the “common heritage of mankind” (Moon Agreement of 1979, article by Timothy G. Nelson on CNBC), why is there no single unique international programme to achieve this common goal? What are the reasons stopping such initiative? Are military secrets and technology development the only reason?