Didn’t ITV already put in the infrastructure? Aren’t most regions mapped to the same SD one?
Not on Freeview. Only London and Granada match the relevant region. If you live in the South West, instead of getting ITV West Country, they have ITV Central (West) and viewers in Norwich receive ITV Meridian on HD instead of Anglia. Granada goes out in the Border, Tyne Tees and Yorkshire regions.
Guess
this is wrong. Wonder where they got the information
That list refers to all the regional variations that are transmitted by ITV. Not all of them are available on Freeview. As of today it also happens to be out of date as ITV launched more variations of ITV HD this morning.
For example, I live in the Anglia West region. On satellite (Sky/Freesat) until today we received Anglia East on ITV HD, as that list says, and as of today we now get Anglia West in HD. However on Freeview we get Meridian South East on ITV HD.
It's because ITV HD is carried on the BBC owned 'PSB 3' multiplex, which was the original Freeview HD multiplex and the only HD multiplex with full national coverage. When it launched ITV only transmitted a few 'macro' regions in HD, and BBC One HD had no regional variations at all (still the case in England), so the multiplex was setup with enough encoders to cover all of ITV's macro regions.
Since then ITV have launched HD versions of most their regional variations, but Freeview is stuck with the old variations due to a dispute between the BBC and ITV over who should pay for the new encoders/infrastructure. The BBC thinks ITV should pay for it as they're the ones asking to add more regions, but ITV refuse to pay the full cost as the BBC will also benefit from it when they eventually launch regional versions of BBC One HD, effectively giving the BBC free encoders. So we're now stuck with a silly situation where many areas have completely the wrong ITV region on Freeview (which has the most viewers), but the right one on satelllite.