I think most Freeview guis do offer to distinuish between “scan for new channels” and “complete rescan for all channels”. In my view, the vast majority want the latter, and it should be the default.
But even the tuning menus can be hard to find. Whilst considering a contribution to this thread I have spent the last half hour, navigating menus, trying to find tuning options for my Panasonic Firefox OS smart TV. Could not find them at all, was driving myself nuts.
Eventually I twigged, because I had been switched to an HDMI input when I started browsing the TV setup menus, tuning options were removed. Not just greyed out, literally removed, the tuning options were invisible, they did not exist. Once I switched back from HDMI to TV, DVB tuning appeared in menu->setup.