As far as I know it depends on the operators choice. You may find even 747-400 not being CAT II capable ( i.e. Air India till 1999, FRA incident) and there are some southern europe / north african based companys still doing fine with CAT I. It's cheaper for them not to fly or to divert in conditions less than CAT I than to buy and maintain the equipment and keep the crews current on CAT II or even CAT III all the time.