I disagree entirely! How can it not be riskier?
I too am a bit perplexed by this comment.
We have had a few high profile incidents. One of which caused a huge backlash from the DI grade. Many handed their licenses back. At the other TOC I work with there has been calls for the DIs to get a separate license because of incidents. There will always be an incident of some sort but there are actually relatively few that occur with your Instructor.
Instructors are constantly monitoring their Trainees and yes they do mess up but you normally catch it or see it happening before the Trainee does. That constant monitoring and instructing means you are less likely to have an incident. Drivers tend to have incident when their concentration slips or they get distracted. With a Trainee you are constantly looking out for everything.
Weirdly the Trainee can also prevent an incident. You have two eyes in the cab and speaking with many Trainees they will tell you a few stories where they noticed something that their DI didn't.
When you have a Trainee there is a point where it is a high risk. That moment is when you have trust in your Trainee and tend to let them have more control. This comes from overconfidence in your Trainee and you forget that you are still in control over the train.
There is also a case of 'Workload Management' An Instructors workload can actually decrease over time. They are often off the roster for static days and spend time route learning so your off roster taking trains off people. This reduces your workload.
You also spend a lot of time teaching. Your rules, traction and routes go through the roof. That constant repetition increases your skills. Increasing skills, reduces incidents.
You also spend a lot of time actually doing it right and very strictly by the book. Those Swiss cheese holes are less likely to occur because you are constantly showing your Trainee how to do it the right way.
And, if your TOC is doing it right, the more experienced Drivers and those with a more professional attitude etc are the ones who get the job.
There is 'risk' but no where near what crew room gossip reports. Don't get me wrong I know more than one DI who jacked it in because they didn't want to risk their license anymore. I certainly believe that this is more to do with the way DIs are treated and that there should be an acceptable level and understanding of the risks involved; hence the second license.
Hope that helps.