A factor in the history of misfueling jet fuel into piston aircraft was the word "Turbo" appearing on fancy stickers on the side of the engine. Fueling people were understandably confused. The requirement for the identity of the required fuel has been in place for a long time, but some people still overlook it. Unfortunately, some aircraft types lend themselves more to this error, as a very similar version of the aircraft is available both gasoline and jet fuel. While flying the Lycoming powered DA-42, I paid extreme attention to what fuel was being put in.
Sadly, the pilot had multiple opportunities to detect this error, and not fly the plane that way. I've been as guilty as the next pilot of sometimes just jumping into a fueled plane, without confirming what was put in. More recently, I've been simply looking at what the label on the supply of fuel says is there. You also have a super opportunity when you pay for it.
That said, it seems to me that it was a crash shortly after takeoff associate with an engine failure which was the fatal event. Misfueling was a large causal factor in that crash, one which was a failing on several people's part, detectable and preventable. But it left the pilot as being the sole person who affect the outcome, and it did not work out well. I accept that an EFATO (as opposed to an EFA cruise flight) will nearly always result in a damaging off airport landing, but few need to be fatal.
How pilots handle and preplan for EFATO is a separate and worthy topic as to misfueling. Every now and again, I'll be taking off, knowing that that takeoff has a much less good possible outcome in the case of EFATO. I'll usually adjust my technique to optimize things. I certainly witness takeoffs where I think that the pilot missed opportunities to make the takeoff more safe and survivable were an EFATO occur.
This sad event is a good reminder on two topics of airmanship....