I think that there are two different kinds of rules in your example. In the Kanda → Tokyo example on the Chūō Rapid Line, my understanding is that the prohibition is a station-specific operational measure introduced to reduce crowding. That’s why it is explicitly announced and posted at those stations. It’s not framed as a fare issue, and breaching it doesn’t result in a fare penalty under the 運送約款.

By contrast, the Conditions of Carriage mainly govern fare settlement — entry station, exit station, and specific special cases such as same-station return or circular lines. Outside those special cases, Conditions of Carriage generally don’t prohibit temporary overshooting or direction reversal, as long as the passenger enters once, exits once at a different station, and pays the correct origin-to-destination fare.

That distinction is why, in most situations (including terminals where trains reverse direction), travelling A → B → reverse → C is treated as a normal A → C journey, whereas in a few explicitly announced locations the railway asks passengers not to do this for crowd-management reasons.

So my understanding is that the Kanda example is an operational exception to the general case that one can go in reverse and turn around under the Conditions of Carriage.