Why has it taken so long for the U.S. to realize that a national Lockdown is necessary to prevent the spread of Covid-19?

Lockdown is not the answer, otherwise the lepers would be running the streets and all the healthy would be quarantined.

Do not know if I would believe anything the Chinese government tells us they are not anymore open and honest than our government.
The experts placed people on ventilator oops that was a mistake very hard to get them off.
In New York they put cova positive people in nursing homes where the old elderly and preexisting conditions were very high already before being exposed to the virus in what fantasy land does that remotely make any scents
We as a nation could not lock down Seattle, Minneapolis Chicago Atlanta or Los Angeles what remotely makes you believe we could lock down a state let alone the entire country
Just saying

The purpose of the lockdown was NOT to stop the spread to prevent overloading the hospital system. China locked down Wuhan for domestic travel but, NOT international travel. Americans surprisingly at first went along with the lockdown. Politicians destroyed the trust they were given by continuously changing the goal post and saying anything to maintain control. They always state "follow the science", which version?

No, I disagree with the economy needs to open back up

I guess a lot of it stems from our system of government. We are a constitutional republic, not a democracy, with states that have rights.
I know that pesky constitution always gets in the way of liberals, but still its there.
So, lets talk about the science and some general facts. Up until February 2020 the science community had said that lockdowns were unnecessary, would not work, and cause far more secondary damage. For some reasons almost all of the experts that agreed with that changed their minds in late March, 2020. Not only that they pretended like that had never been against lockdowns, but there is all kind of evidence showing they did.
Now with the benefit of time we can see that the states and countries that didn't shut down are doing better.
India in fact is not doing as well as you implied and if you believe the China numbers you are likely to believe just about anything that anyone might tell you.
I will never understand why people wanted to lock down South Dakota because New York and New Jersey are doing so awful. Now we know that the governors of the hardest hit states enacted terrible policies and no amount of blaming Trump will erase that.
The "experts" in charge have said that Trump has done everything they have advised and more, like the travel bans, and because of that saved tens of thousand of lives if not more.
I realize that blaming Trump is far more important than anything else, especially with an election coming up, but that doesn't make a whole lot of sense. Especially when you consider the experts kept getting things wrong and changing their advise.
This is another reason why fake and incorrect news and reporting is so dangerous. Studies have shown that the democrats are highly misinformed about the virus because of their news choices. Its really sad.

Because we are the product of a nation brought up on the idea that we have rights, and our rights trump common sense and what is good for everyone. This is not new, read up on some old SCOTUS cases Jacobson vs Mass. Set in 1905 during the small pox era.

Since when did the US military become a bunch of sheeple?
The latest admittion from the CDC that of the 180,000 deaths, less than 10,000 died of only China flu . The rest died with (maybe) China flu in them at the time . Upwards of 90% of positive tests were actually 90% . This was not a pandemic it was a plandemic. The only reason for the lock down was to destroy the country

Many people absolutely refuse to consider doing anything that may inconvenience them regardless of how short the duration or the minimal impact on their personal lives. How does that saying go? "An ounce of prevention prevents a pound of cure."? On the other hand, verified and validated studies have shown that federal policies such as seatbelts, helmets, designated driver and so forth save lives and yet, it seems that many deliberately choose to defy any rule or policy that benefits all. And the very same individuals wonder...

Several assertions here that you can't verify. 1. Beiging and Shanghai reported no cases of Covid. Doesn't mean that didn't have 30K unreported cases. 2. Cases in India are way less than any other country. If you don't test you won't know what you really have. 3. Why can't we do these things to save lives from Covid. So you save 30K lives to covid but suicides go up by 40K, Murder and mayhem increase 100 fold, and hundreds of thousands permanently lose there means of supporting there family.

You can't look at this through a straw but from 30 thousand feet open eyes and minds. There is something in-between that saves the most lives. Not just Covid lives.

That is a question with a conclusion, the facts are not in evidence, the lockdown is relsted to thr hype and hysteria byva left fringe media, and is not based on scientific evidence.
The question is as lame as "when did you stop beating your wife?"