> Bridges are not safe because of any government agency
Building a bridge is one of the most heavily regulated things in the USA.
For details, see: https://www.fhwa.dot.gov/bridge/nbis.cfm
Every single bridge in the USA is documented, listed, inspected and regulated. There's even an entire division of the US Military that helps out: The Army Corps of Engineers. So its multi-agency, multi-department, and even includes military service members.
Bridge Building might be the only thing more regulated than Airline safety in this country.
> because mechanical engineers design them to be safe.
Civil Engineer btw. Not Mechanical. And Civil Engineers need to pass a strict level of training and licensing to practice in the USA. Granted, this is on a State-by-State basis rather that on a national basis (like Bridge-building).
But its still a government regulation, even if its State-wide instead of Federal.
https://www.nspe.org/resources/licensure/how-get-licensed
All 50 states require 4-years of work experience before you earn the title of "Professional Engineer". And that's the title you need before you can lead something like a Bridge-building project.
Not only are bridges highly regulated, but the people who are allowed to build bridges are highly regulated, at both the State and Federal levels.
----------
Now I'm not saying we enforce the highest regulation standards upon our CPU manufacturers. I'm basically saying "Stop coming up with bad examples". The incredibly safe examples you have brought up so far (Airline safety and Bridge Building) are the result of years of Government regulation and laws.