Whether this is an engineering, safety, political or scientific principle is not really important for my point. I used the word scientific principle because I first learned of it in a science textbook in a chapter discussing side effects of pesticdies, but obviously it spans multiple disciplines.
It is in constant use, although there are probably places in the world where it is given more attention than others. The United States is absolutely not the world's bastion of the careful and incremental application of new knowledge, this may be why it is unfamiliar to you.
A prominent historical example would be the reluctance to use the first nuclear bombs before establishing a consensus on whether such an explosion could ignite the atmosphere. Contemporary examples would be e.g. the care taken when using a new, promising drug prior to rigorous animal and human testing or the reluctance to use new useful chemicals and materials (e.g. nanoparticles) everywhere due to the possibility of long-term health effects like cancer risk.
This is the only phrase I disagree with in your very thoughtful comment.
When was 'the cautious route' ever a scientific principle?