It could be argued that simply following the existing rules would also lead to a reduction of accidents.
You sound like a railway executive ;-)
A core principle of safety system design - whether nuclear reactor, airplane, railway or otherwise - is defense in depth - multiple redundant standalone systems.
I would argue that the railway rules are more like a set of dominoes. Not only is there often no redundancy, one failure can trigger further failures. Too much reliance on human performance where oversight or backstopping by automated technology ought to be in place. It comes down to money not spent.
The biggest reason why Burlington happened was the lack of a sterile cab. I get that coworkers want to be buddy-buddy, but at the same time in a safety-conscious position like theirs distractions - such as the conversation that they were having with the third man in the cab - have been shown time and time again to be problematic and worse. There is a reason why outside electronic devices are banned in the operating cabs of all railway equipment in Canada.
No one should assume that those three were discussing the Blue Jays. There are other incidents documented where a 2-person crew (without visitors present) committed errors simply because they got engrossed in a discussion of what they were doing, and lost situational awareness.
The risk of too many people is complacency - one person figuring the others are still watching what's happening. But whenever the work is split across even two people, the risk is that no one person can handle all the inputs. Which is different than one person performing the work and the other overseeing as a second line of defense.
In short, whatever PTC or equivalent is installed on GO and VIA, it can't come too soon.