Why are we always comparing people to Britney in her prime whether it's looks, fame, dancing etc? It's 2012, not 2002.
That's because Katy and Carly look their age and Britney definitely doesn't. She was good-looking at her peak, but not anymore due to poor aging.
And Britney is wearing plenty of makeup in that picture you posted. She just looks tired and old. Katy doesn't even look that different in that pic without it. Her skin is even unlike Britney's, which is full of spots and skin damage.