I will disagree with you on this point. In four years of use, I have never lost my key fob. In 1+ year of use I have lost my smartphone twice, mainly because it is too large to fit in my pants pocket conveniently. I don't need to carry a key fob because it is small enough to fit conveniently in my pants pocket where it stays, but not so the smartphone that I do have to carry. If not for the smartphone, both my hands are conveniently empty. Mine is sufficiently waterproof because it never leaves my pants pocket, I have not needed to even replace the battery in four years, it never needs to be charged, and I don't have any idea what the replacement cost is because I have never needed to replace it. I do know what the replacement cost of a smartphone - several hundred dollars depending on the phone.