It depends a lot on the terrain and specific area whether a typical VHF/UHF ham radio will work. The range is much longer than cellular, but it is quite LOS, and repeater/digipeater sites with good coverage tend to be at established antenna sites for commercical broadcast or telecom. There'll be some more remote sites of course, but infrastructure and LOS is still more or less required. With many popular recreation areas up in uninhabited mountain valleys with no infrastructure and where building stuff is often prohibited, the chances of hitting a site aren't great unless you happen to be below a mountain microwave site or such. At least without hiking out of the valley, but that's hardly a condition you want to put on yourself for an emergency communicator.
That said, it's not a bad thing to carry in your car, as there are plenty enough dead spots that would likely be covered by packet radio. It's just a lot less clear how to get help.