I can't be the only one this happens to and yet I haven't seen this mentioned during my research:

I recently booked the Royal Park Haneda Transit for a family member trying to keep an overnight layover super simple. Only that I booked the landside one instead. This seems to happen often enough that they have a process to escort visitors past security without VJW which is what happened in this case (including a second unrelated guest).

So my mistake appears to be that the booking function for Royal Park Haneda Transit is tucked away at the very bottom of the Transit Area page. The transit booking process includes a transit area disclaimer and the only plans are 6 and 12 hours. The other standout feature is it's very booked.

Everything else will book the landside part.

Do I have this right this time around?