In my experience 'shared residence' has become a somewhat meaningless sop. If parents live in different countries, or even more than an hours drive away, it is difficult to see how in any real sense 'parenting' is 'shared'. One parent by default will be the primary carer, provided the home, doing the washing, cooking the tea, ferrying around to activities etc, etc. All the drudgery of parenting in fact, but what makes up about 90% of what is valuable to a child - that a parent is there, doing stuff, looking after the child, making him/her feel loved and wanted.
It is much more difficult to do that when living far away.
I am afraid the real problem will always be that when some parents separate, they can't do it well. They let their hatred, resentment and/or fear of the other leak out all over the place. Sometimes these strong feelings have an objective basis, when a parent has been abusive. But more often (in my experience anyway) neither parent has been any worse than the other. They just hate each other and are either unable or unwilling to understand the damage this does to their children.
The law never has and never will be the arena to sort this out. I don't know what the answer is. Licencing parents is the only thing that springs to mind but that cure would be worse than the disease.
But thinking that if we only just had a different wording of the legal test that would be the magic wand that sorted everything out, is delusional and wishful thinking of the most unhelpful kind.