Firefox (uniform tab sizes) seems to think that the midpoint of the dragged tab crossing another tab's boundary is sufficient to swap their positions. Google sheets doesn't care about the column midpoint, instead swaps column positions as soon as the cursor intersects another column while dragging.

Both work pretty intuitively imo, due to immediate feedback (you know where the tab/column will end up before the drag is released).. despite the control behaving quite differently 🙂