"Would you rather I quoted The Daily Fail?"
You pretty much did, just its opposite.
"Regardless. Poor is poor is poor."
Not in this case. Absolutely and relatively are very different. You can be poor or not measured absolutely (and in that case we have effectively if not absolute 0) compared with relatively where we will always have poor.
"A country as rich as ours shouldn't have poor"
As pointed out by others the measurement ensures there will always be those classed as 'poor'. Just as 50% of schools will be below average no matter what we do.