City, as in big city, and country driving are two totally different situations..
They are testing the situation on the Isle of Wright. Thats a location that seems likely to me to have almost an ideal situation for GPS. Probably very few if any tall buildings or underground areas, and even the largest buildings seem likely to be as large as the smallest buildings in most big cities.
Many people who dont live in big cities never go driving in them. So their own GPS which looks and is accurate enough to spot lane changes under local use seems accurate enough to them.
But its an entirely different situation in cities with lots of tall steel buildings, (urban canyons) or inside a network of streets where traffic often descends underground to get from point A to point B.
Newer phones can and sometimes are more accurate but there are hard limits to the coverage -
Outdoors, coverage is fairly good, but accuracy declines greatly in dense cities,
exactly where people are forced more closely together. (Risk of infection is by all accounts very low outdoors)
1. whether a fix is available or not largely comes down to whether somebody is outdoors or indoors.
2. in the places where people would be most likely to pick up infections, (indoors) it is basically guaranteed
to either be unavailable or very very inaccurate and unpredictable.
Nonetheless, if
this system was available, it would invariably be used more than its accuracy would dictate it should be.
Does anybody remember the report that came out several years ago from the UK government on the safety of cell phones? That was a good example, of a badly done investigation of a subject that clearly had only one decision in mind and was determined to block off any adult discussion of the unknowns.
It depends on how it's inaccurate. Yes, if it doesn't generate enough positives, when it should, then it will allow the infection to spread too much and be useless, but if it errs on the side of caution and generates more positives, than necessary, then it will reduce the rate of infection. If everyone on the same train carriage goes into self-isolation for a week, because one person had it, then any of them who have caught it won't infect anyone else and it would have done its job.
GPS is useless for tracking. The inaccuracy in a city can easely be +/-80m (if not more with high buildings around). A much better option is to use triangulation between cell towers.
Thats what TruePosition used to do but a few years ago they were pushed out by some other folks and I dont know if it emerged why or not.