Safety training for training's sake is no guarantee of fleet safety.  But by default, lack of safety training and proper instruction does increase risk.  Example:  We assume a new hire is competent in preparing a drivers daily log because they've been driving professionally for several years - until we discover the previous employer(s) had no auditing process to catch errors or falsification.  We find hours of service violations too late after a fatal collision.  Now the company is being sued for millions.  Was it worth the risk?  Don't roll the dice with safety.  Rule of thumb:  Always assume incomptency unless trained or tested otherwise.  Never assign safety responsiblities until buy in and understanding have been established.  Sometimes this will require more than a mere acknowledgement form.  Manage for results - not mere compliance.