Crosstalk analysis, Altium vs. the World
It's quite simply that Saturn has no idea what chips/passives are connected to the target line. If you look at the 2nd example, your driving voltage is 3.3 volts and it couples 1.65 volts to a track that is effectively equi-distant between source and ground. It cannot produce an answer other than 50% of 3V3.

Any driving node on the target line is going to look like a few tens of ohms and this will decimate any cross talk and convert what would have been a cross-talked voltage pulse to a current sunk into the driver.