Think about it this way, though.
How many of those carriers use the same technology for their network? IIRC, O2, Orange, T-Mobile, etc., all use GSM. Possibly, they may use different bands, but still use GSM. This allows Apple to use the same hardware to be used on those carriers.
US? Not so. ATT and T-Mobile. That's it. Verizon is screwed because of CDMA. It would cost more to Apple to make the phone with two different sets of hardware than to cover Verizon's market. So while people think on a business perspective that the more marketshare, the better, they aren't taking into account how much it would cost to make the unit, and if that costs more than what they'd make in return per service, it's not worth it.
BL.