Accident or incident because of human error(s)?

All of accidents or incidents are happening because of human errors?
We (human) create work(s). From a work, it creates job and processes to create the completed work.
The processes create several series of work sequencing.
Each work sequences have its act and condition.
Perfect act with perfect condition will result to be no incident and no accident.
Bad act with bad condition will result a catastrophic accident or disaster.
Good act with bad condition will result to be accident, usually a bad accident.
Bad act with good condition will result to be accident, usually a bad accident.
Recent accidents;

Bridge Collapse at Penang Second Bridge Project was happening because coincides of bad act(s) with bad condition(s).

Similarly to the accident of boat capsize at Belaga near Sungai Rajang, Sarawak was happening because coincides of bad act(s) with bad condition(s).

YES, it easy to say than done.

At every point of the processes we need to make decision that will be determine the degree of sureness on the act(s) and the condition(s).

For the boat capsize, why the decision allows to carry overloading passengers?

For the bridge collapse, why allow user(s) travel under constructed bridge? Do the temporary structure(s) (scaffolds) are checked and installed as per design load? Do the materials use (scaffolds) have defected part(s)?