My first Post! Excuse me butting in;
I think 2 things have been overlooked here by both sides of the argument.
1. Consider the first word of the term "Commercially Available": it means you have to pay for it.
2. What is a GPS device.
Looking at item 1, if I can use the analogy of old-school navigation using a paper map, then the first thing you obviously need is a map. This means that someone has to survey the terrain and its features to an acceptable degree of precision for its intended purpose. This might be by surveyors on the ground, aerial survey, or a mixture of both. They then have to transfer this data onto its graphic format and organise its distribution to users. They aren't going to give this hard-earned information away; they SELL it to the consumer. For the sake of argument, lets call the map a database. The second thing you need is to know where you currently are on the terrain/map. Generally, this is a given, because we all know, depending on the journey we're making, "I'm at home", "I'm in Glasgow", or "I'm at Gatwick Airport". Thirdly, we need a sense of direction; this might be as complex as a compass and Inertial Navigation, radio beacons, sail west at 10 knots for 6 hours, or just "walk to the church and turn left on the High Street". Whatever, we need positional information about where we are and its relationship with where we want to be.
Looking at Item 2; what is a GPS device? Its got 2 parts, the first part is a receiver. It doesn't transmit anything. I gets free-to-receive signals from Global Positioning System satellites and by analysing differentials in the signals it determines where it is on a vast featureless ball. This is its positional information. It does this to a high degree of accuracy, but it has no idea that it is in Wigan. That's where the second part comes in. Remember our database? We need to COMMERCIALLY buy, or rent, a database. A true GPS device includes a software database which you paid for when you bought the GPS from Halfords or PC World or had it included in the car you bought from Honda, or the plane you bought from Cessna. You either paid for it once at the shop, or you subscribe to an update service, but its stored in the GPS device. Depending on need, you bought/subscribed one with your country's maps, continental maps, roads, seaways or whatever. A SMARTPHONE is NOT a GPS device. It EMULATES a GPS device by incorporating a GPS receiver, which (remember) does not transmit. The PHONE transmits to a terrestrial phone-mast using your cellphone-data allowance, the network verifies your entitlement because of your (commercial) monthly data package, and sends you a map of where you currently are, from a terrestrial phone-mast. Your phone does not carry around a database of the world, but they will RENT it to you as you need it. If you drive into the middle of the ocean, or the desert, or probably a Welsh valley you will continue to receive a GPS signal but you will lose your phone signal, you will lose your rented maps, you will lose your emulated-GPS. The phone's space-based GPS receiver is still working, but it no longer has a terrestrially-provided map to relate to.