Why don’t they make a unified line of products?
How much time do you have?
When compared to most consumer products, model trains are a very low volume specialty product produced by a cottage industry.
Do you realize that not one US based model train company is publicly traded? Most are totally privately held, only a few are part of larger companies.
And that world wide only a few are big enough to be on the stock markets of their countries?
Some of the tooling producing these models is brand new, yet other items are being manufactured with tooling that is 20 years old, 40 years old, and even older in a few cases.
Factors of tooling cost, high level of hand work assembly, limited market, unlimited number of possible items to be offered, all make this a very difficult business, mostly operated by modelers themselves to some degree or another.
And the customer base has a very wide range of needs and wants in terms of price vs features.
Many of the bigger companies Bachmann, Walthers, Athearn, try to serve all of these market levels, so they have high end, mid range, and budget models in their lines.
AND, they have just recently realized the need to clearly define those levels to their customers. The historic reasons behind the growth and evolution of this hobby and its business side would take pages to explain - but I could fill you in. I grew up in and round this hobby and business, started working in my first hobby shop in 1970, at age 13. By age 21, I was managing a train department…
Just know and accept as few basics and you will figure it all out.
First, not every product from a given company will be of the same quality, detail, and prototype accruacy. Again they are getting better about defining detail/accuracy levels, but there are still variations.
Second, because of the private ownership of US railroads, there are endless numbers of locomotives and railroad cars to model spread over the 160 plus year