Lockdowns work if:

• They start early.
• There is high social trust.
• There is enforcement.
• There is light at the end of the lockdown tunnel.
• They are mostly done in warmer months.
• Most people are fairly healthy/non-obese.
• There is not tons of political polarization.

So, in the US, and many other places lockdowns de facto do not and cannot work no matter what kind of cool science shows that they do under ideal conditions.