It doesn't work like that anywhere in OSM. I can cross a road that I'm
not allowed to drive on. The router does not need to know anything
about the road that I'm crossing and I can always cross a road that
I'm not allowed to enter.
It would make mapping extremely awkward if that were not so.
You're taking one example. Please don't extrapolate it to make it appear
it's every case.
Information about the way you're on or crossing can required for
numerous reasons. My original point, which seems to have got lost
somewhere, is you can determine where you are & where you need go from a
single node. Even on a roundabout.
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