Do those things cost trillions of dollars? I don't think so. Each country could probably commit a couple hundred million to this and be better off than a complete shutdown.
We can't create enough bed space, vents, ECMOs, in the next 6 months. We can't train enough doctors, nurses, etc in 6 months. So we play the hand we're dealt, and choose a mitigation strategy that doesn't result in 70M worldwide fatalities (6M in the US).