Safety incidents happen a
lot.
> By 1960, hundreds of American scientists and technicians had been hospitalized, victims of the diseases they were trying to weaponize. Charles Armstrong, of the National Institutes of Health, one of the consulting founders of the American germ-warfare program, investigated Q fever three times, and all three times, scientists and staffers got sick. In the anthrax pilot plant at Camp Detrick, Maryland, in 1951, a microbiologist, attempting to perfect the “foaming process” of high-volume production, developed a fever and died. In 1964, veterinary worker Albert Nickel fell ill after being bitten by a lab animal. His wife wasn’t told that he had Machupo virus, or Bolivian hemorrhagic fever. “I watched him die through a little window to his quarantine room at the Detrick infirmary,” she said.
> In 1977, a worldwide epidemic of influenza A began in Russia and China; it was eventually traced to a sample of an American strain of flu preserved in a laboratory freezer since 1950. In 1978, a hybrid strain of smallpox killed a medical photographer at a lab in Birmingham, England; in 2007, live foot-and-mouth disease leaked from a faulty drainpipe at the Institute for Animal Health in Surrey. In the U.S., “more than 1,100 laboratory incidents involving bacteria, viruses and toxins that pose significant or bioterror risks to people and agriculture were reported to federal regulators during 2008 through 2012,” reported USA Today in an exposé published in 2014.
In 2015, the Department of Defense discovered that workers at a germ-warfare testing center in Utah had mistakenly sent close to 200 shipments of live anthrax to laboratories throughout the United States and also to Australia, Germany, Japan, South Korea, and several other countries over the past 12 years. In 2019, laboratories at Fort Detrick — where “defensive” research involves the creation of potential pathogens to defend against — were shut down for several months by the Centers for Disease Control and Prevention for “breaches of containment.” They reopened in December 2019.
From https://nymag.com/intelligencer/article/coronavirus-lab-esca..., many links to sources and more details in the original. The USA Today story is particularly interesting though (https://www.usatoday.com/story/news/nation/2014/08/17/report...).
Humans make mistakes. Accidents happen. And even at the most secure labs in the US, sometimes people die. Yes, we (hopefully) learn from our mistakes; a fatal accident in the 50s or 60s doesn't mean these things still happen today. Maybe (hopefully!) all those recent breaches and safety incidents were relatively minor. Perhaps China is much better about such things than other nations. And even if mistakes can happen that doesn't mean a mistake happened here, in this instance!
But if your prior is just "BSL-2 and higher labs are safe, they would never have a containment failure" I think you may want to re-evaluate it.