If I'm going down the road at 60 mph, and I want to measure the difference
between my speed and that of the road, I will get the same answer whether I assume:
1. That the road is not moving, but I am OR
2. That I am not moving, but the road is.
Both are "equally valid" if all I'm trying to determine is an absolute difference in speed.
But that doesn't mean that either proposition is "equally (likely to be) true."
Even LESS does it mean that BOTH are true (i.e., that BOTH my car AND the road are not moving). There could be no speed difference if that were true.
Just one of many things you seem incapable of understanding. I would withdraw from the discussion if I were you too, and if I only wanted to pontificate, rather than understand, or God forbid, answer questions if I spoke nonsense.