Because people didn't do what they were told to do, and the government screwed it all up. Some state governors did nothing.

The US's categorical inability to implement the basic functions of a state are not an indictment of those functions

None of this changes the fact that in hindsight the lockdowns were extremely costly in several ways and proved to be mostly ineffective.

You know what's more costly? Dying.

> mostly ineffective

The United States government is mostly ineffective. Again, America's inability to do most functions of government correctly is not an indictment of those functions.

Also, it should be said, the US's prolonged mishandling of the Coronavirus pandemic had lasting economic impacts because people willingly chose to stay home to avoid getting sick, not just because occupancy limits were lowered for many businesses (what you mistakenly call a "lockdown"). Had the US enforced coronavirus restrictions better and if Americans didn't selfishly refuse to follow the rules, the economy would have taken far less damage than we chose to inflict upon ourselves.

Even China's extremely draconian zero-COVID policy lockdowns, with martial law and doors welded shut ultimately achieved very little. When I say we all got COVID anyway, I mean pretty much everyone in the entire world did.

The goal in the west was never to eliminate covid, it was to slow the spread of it. School closures are an effective means of doing so (if done pre-emptively) because schools are one of a few places where an entire towns social network crosses paths at the same time.

We have known this for over 100 years, since the Spanish flu pandemic. Denying this is simply anti-scientific and motivated by your political beliefs