So why has this become so commonplace you'd think with all the safety gadgets this shouldn't happen.

First 2 look like the operator didn't put the boom outrigger switch in the neutral position while washing out the 3rd not sure just looks like stupidity.  All three just look like someone got distracted by a squirrel

Like I am saying over and over again: You can not and should not make pumps idiot proof. You have to take the idiots away from pumps.

^^^ Totally agree with you Dipstick

Unfortunately, there isn't a way of making these machines completely idiot proof, without making damn near useless. Proper training and technique, while avoiding complacency is key.

Looks like a decent amount of short rigging, lack of proper dunnage placement, improper outrigging setup, ect. 

we are calling these guys idiots , but surely none of us know what really happened , how many times have all of you raised the boom to washout without putting down the rear outriggers ? me myself I have done it thousands of times, one time I had a swing brake fail and luckily I caught it , I was on a slight angle and the boom drifted luckily I caught it before it got completely over the side , I have also encountered a joystick short out and take off swinging right and would not stop , only thing that saved me was the estop system .So its not always idiots , may be in all these cases , but every now and then mechanical issues can cause accidents.

So if we would all have a good ''concretepumpingschool'' to go to we would learn these kind of things right? So we would all know you can have a swing break fail for example..  Because the system we have now where you are as good as the other operator that was willing to train you is clearly rubbish..