I wouldn't necessarily say that, one of the problems is that because it's a website it can't do proper notifications. To see if you've been called in the virtual queue you need to keep the website open, and check it regularly otherwise you'll miss it, If it was a proper app, whether a ported version of the Carnival/Princess app or something else, it'd be able to generate actual notifications on your device. For some reason P&O/Cunard are some of the only Carnival brands that don't have one.