"if this is just unique to Sony"..."Sony is incompetent"
More likely, Sony simply outsorces their web properties to some outside teams, which do not have proper expertise in building secure websites. This theory is especially make sense if you look at what properties were hacked - they're mostly local-market websites. So, I'd say, the only one hacked property Sony must really be embarrased for is PSN, hands down.
I worked with a guy about 7-8 years ago who went onto to manage an Indian outsourced team for the SonyStyle web store. He was terribly frustrated with the situation and the quality of the engineering staff. Stopped having lunch with him as every time it seemed to devolve into a rant session. Note that he was Indian born/educated himself. It was sad as we collaborated closely on a project for over a year and he was one of the sharpest, happiest, most positive engineers I ever worked with.
More likely, Sony simply outsorces their web properties to some outside teams, which do not have proper expertise in building secure websites. This theory is especially make sense if you look at what properties were hacked - they're mostly local-market websites. So, I'd say, the only one hacked property Sony must really be embarrased for is PSN, hands down.