The problem is that our toys are made in job shops. It's batch work.
One week they make Lionel milk cars and the next week they make DVD players or cell phones. There is no continuity of engineering, no experience of what was done previously. That's the way it works if you use a different factory every time. Even if you use the same factory, it's been so long since the last batch that the production workers and manufacturing engineers are building things that are new to them, things that they have never built before.
The only way to fix that is to use the same factory, same workers and same engineers every time - and give them a much greater volume of production.
Since our trains are not built in sufficient quantities to keep one factory running, we will keep seeing problems like this time and time again.
In manufacturing terms, the factories either lost the recipe, or never had it in the first place.