How does Freight train work?

[shell swallow]

Sometimes train delivery often has problems, is it me who is not managing the train line well/ is it a bug?
This game still uses the system
Resident -> Industrial -> Commercial 🔁
Right?
#1085157639706640414

[stiff niche]

Freight trains only go between industrials and commercials

[shell swallow]

In the photo I have made a special train line from industry to commercial

[shell swallow]

And for some reason my train line is always quiet, even though other public transportation is operating.

[shell swallow]

Somehow this feel Bug
Why not create a system like residents?