well "ignorance" pretty much sums it up. If we didn't draw it out in color pictures or put it on a movie people wouldn't do what they are supposed to or do what they are not supposed to do.
If we didn't have training we would have idiots out there working with no safety glasses with a grinder in their hands chopping away on a piece of steel with the electrical cord laying over top of where they are cutting. The outcomes would not be good.
Safety training is very important part because if you are not enough trained for particular work then you have to face many injuries during your work. The work wear are also compulsory to protect yourself from injuries. http://www.worklinesafety.co.uk/ This is the place where you can get various types of work wear according to job category.