You have experiments to rule out alternatives. They do not ‘prove’ anything. You have statistics to tell the probability that you’ve figured out what is causing something.
Why would an experiment not be approved? Imagine you are expecting a baby. Imagine you are offered the opportunity to take part in an experiment in which half the subjects would be given a drug that is suspected of adversely affecting the baby. In our country that study would not be approved.
That’s why some countries conduct their studies in other countries. Apparently that is why some countries develop drugs in other countries. Some people think we were doing that in Ukraine and China.
It happens all the time!
17 women took part in the U.S. in the thalidomide study! It was approved in other countries, and it was only not approved in the U.S. because of one woman. If she did that today, she would be fired.
There was another drug (I can't remember the name.) for woman that was approved in the early 2000s. The guy at the FDA refused to approve it, for many reasons. The company called his boss, and she overruled him. Even though he was a top employee, he left shortly after that.
How many women died while they were researching and approving "the pill." It was a lot!
Tylenol was released in 1955. If they never researched how it impacts pregnancy before it was approved, that means every single pregnant woman who took it was doing the same thing someone in an experiment, just not collecting the data. How is that any different? Do you think no pregnant women have taken it?