For US models (which do not now include an indicator at the charge port, as the EU models do), it seems that, without having to modify the vehicle significantly, they could have "dual-purposed" the top-of-dash indicator which serves as part of the park assist system, to implement an externally visible charge/status indicator.
The dash board element could have been installed for all vehicles, regardless of whether or not the vehicle included the park assist function.
Perhaps EU regulations oblige an indicator right at the charge point. If not, they may have created an unnecessary complication/expense by implementing what they did for the EU. Hard to know what all their constraints were. The design group probably didn't include their "A-team".
Since the parking indicator includes two (left & right) sets of multiple lights, they could have come up with some interesting schemes for delivering status info (charge voltage/current, rate of charge, state of charge, full, interrupted, unable to start, etc.).
For anyone not interested in having this info. displayed, the dash control menu could have provided a means for disabling.