Bad newbies give the good ones a bad rep.

I have been doin my research into the process of becoming a new driver and find that some companies are no longer hiring new drivers out of driving school as they have had bad experiences in the past. I totally understand the reason for companies doing this is the fact that they cant weed out all the 'bad' new drivers and so the newbies get into an accident the companies insurance goes up and their bottom-line profit goes down. I have been around the trucking industry for quite a few years, and have really come to appreciate the jobs that truckers must do, but also the respect for the rigs that these trucks sit behind. My hubby used to drive truck until his accident in '04 which landed him in early retirement due to the physical injuries. So I know how much destruction the big rigs can do if they are not driven with respect. I would have a good job after I finish my training course, if it wasnt for the insurance companies 'dictating who companies can or cannot hire to drive for them.'
My question is this:

Why are less companies (In western Canada) offering new drivers a chance to be placed with a mentor to be given a chance to prove themselves as a driver, as well as get knowledge from an old-hand?

If any of you have any suggestions that may assist me in the start of my driving career in Western Canada, I would love to hear them... Just want to say thanks for all the great advice on these forums!