OK I'll bite.
There is a school of thought with RA / H&S that there is no such thing as an accident. Personally I agree, but in normal language the use of the word "accident" is subjective and arguing over its use is rarely useful.
We also do not like the word "blame" It is for a court to apportion blame and it has no place in investigation. Blame will always hamper any meaningful investigation and prevent access to truth. Looking at outcomes in an emotional sense is also rarely useful.
I also believe that accidents shouldn't happen to anyone. There is ALWAYS a causitive factor and usually there are several. Direct cause, indirect cause and contributory factors and indirect contributory factors. This is often known as the swiss cheese effect.
In this particular case, one could look at the training of the waiter, the equipment he uses, the layout of the area he was working, the temperature of the food when released from the press, his job description and area of responsibility, the restaurant manager qualifications and training, the response to the incident, the legal requirements surrounding response and reporting, etc, etc. Likely you would find inadequate training, supervision, poor equipment and maybe even temperature monitoring inadequacies. In my experience it is rarely the fault of the waiter, and often in my role I have advocated for people like him to prevent "blame" exercises from actually finding and rectifying cause.
H&S is actually about identifying risk and preventing reoccurrences.
If you are truly interested in this look up Human Factors and Root Cause Analysis. There are some fabulous videos from the Aviation industry, who lead the way early on meaning accident investigation.
My personal favourite example is below. A tremendously brave man who has used his own personal tragedy to help prevent others by applying the principles of aviation incident investigation within the NHS.