The "real camera" can be left in a cab too. Likewise, an iPhone photo can be printed. The problem isn't loss of the capture device, it's loss of the (sometimes only) media that stores the image. You can lose negatives too, for that matter, but are unlikely to leave them in a cab.

I tend to prefer what are often nowadays called "single purpose devices" myself, and not just for photography, rather than things that do many functions relatively poorly and are optimized for none, but the problem with digital photos in general and phone photos in particular being relatively ephemeral isn't due to the capture device, or even the storage media really, since they can be and should be backed up; the problem is with overload. We just take so many images, because it's so quick, easy, and in the case of our phones always with us, that we esteem none of them highly and aren't careful to preserve them.