I wonder if that's accurate. I also wonder if this is recurring in the fall, and every year, and whether physical distancing will be mandatory every year?
The key is to buy time, now. To add hospital capacity, develop therapeutics and vaccines, and learn more about the disease...
And it's been a while since American legislators have considered the possibility of torches and pitchforks, so they still prioritize their electability (especially in the primaries, where ideological purism is more important) over social necessity.
Of course the above assumes that immunity really does develop after one exposure, and that the virus doesn't mutate into some sufficiently different form to reset the immunity counter to zero again. The evidence seems to indicate positive things on the immunity front, but it's still preliminary. And as for mutation, who can say?