This outbreak isn't particularly the first time this question has been asked. See numerous papers available through the US CDC on whether or not there was anything that could have been done in this respect regarding the Spanish flu which killed an enormous amount of people globally all the while we were almost all suffering a world war. By 1918 were weird in the bubonic plague doctor mask era. We had at least a basic understanding of infectious disease spread.
These things seem to typically come to a few pillars based on the actions we have seen globally in our latest pandemic.
Career impact on leading politicians. They will be blamed for the deaths or will be blamed for the consequences of a lock down. Neither outcome works well for a politician but dead people make for an insanely effectively political attack against them while attempting to retain office.
Ignorance. Lets never forget almost no politician, the person in power to make these decision is a doctor. In the US we have Rand Paul as possibly the only current federal level politician that is an actual physician. This is a common trend basically everywhere. Most are either business professionals or tied to law if you broke them down at least in western democracies. Not knowing what you don't know can be dangerous and lead to you being mislead or manipulated for the ends of another. Plus there can be a degree of bullheadedness that leads to rejecting expert advice as we saw in the US when Trump enacted the travel ban against the advice of his experts. His experts admitted they were wrong later but what if they were right? If they were or won't will ultimately be decided by history but at the moment they think they were wrong.
Power. Some nations have different power structures and have broad authorities that they don't have in others. For instance the structures for Trump to have done differently in the US was heavily restricted by our 10th amendment giving the states a great deal of autonomy. Some other countries don't have that which is why, if you browse video sites, you see egregious acts such as literally welding people into their homes, being dragged away, arrested, and other acts. The pretty atrocious behavior has happened captured on video in the US as well but largely at the direction of local governments. There have been a number of political officials which have simply seen it as an excuse to expand or abuse power. Governor Whitmer is an example. She has lost in the courts, her executive officials refuse to enact her choices regarding lock downs, has legitimately faced rulings in the state legislature, is facing a recall vote to remove her from office by force, people have planned to forcibly arrest her and put her on a tribunal for abuse of power, but she insists her rules still exist. As history shows...some people just are hungry for power.
Cost vs. Reward. A lock down can destroy an economy. We have already seen this happen in this event. What's it look like if everyone loses their job, starves, or else. Part of this ties into the previous point. China for instance due to both the pandemic but also historic flooding could face mass starvation they haven't seen since Mao was in power. Much of the world receives food aid from nations like the US and the larger EU countries not to mention their own impoverished populations which due to supply chain disruption could face mass starvation. We have seen record level food bank requests for aid in the US. Imagine what a shutdown could do in a less prosperous nation. Leaders have to take that into account. In some cases the cost could literally be their head. In the reward column they could either financially benefit or seem like a strong leader in incredibly hard times. The financial benefits could be something like what is suspected here in the fact that people are facing extremely devalued properties in population centers others can generate wealth through then purchasing them.
I doubt there is some cabal of people making this decision. There certainly is strong communications with allied leaders in various political blocks but a lot of this will, as history will likely show, a combination of ignorance, greed, seeking power, or some combination.
Further reading from the Spanish flu (ill named by some as it also likely came from China) that is pertinent to the conversation..
As civilian infection rates climbed day by day, Krusen refused to
cancel the upcoming Liberty Loan parade scheduled for September 28.
Barry writes that infectious disease experts warned Krusen that the
parade, which was expected to attract several hundred thousand
Philadelphians, would be “a ready-made inflammable mass for a
Krusen insisted that the parade must go on, since it would raise
millions of dollars in war bonds, and he played down the danger of
spreading the disease.
The disease spread like wildfire in crowded troop transports and
munitions factories, and on buses and trains, according to a 1919
report by Sir Arthur Newsholme for the Royal Society of Medicine.
But a "memorandum for public use" he had written in July 1918, that
advised people to stay at home if they were sick and to avoid large
gatherings, was buried by the government.
Sir Arthur argued that many lives could have been saved if these rules
had been followed, but he added: "There are national circumstances in
which the major duty is to 'carry on', even when risk to health and
life is involved."