How would a desktop application know (quoting GP now) "where you spend most of your time and when you are not home"? Surely you see the difference between "the subject uses his computer at home" and "the subject spends a lot of time at his friend's home while his friend is at work"?
The database from the phone is stored in the backup of the phone on your desktop, the database on the phone is inaccessible to software on the phone. Hence it requires a desktop application in order to access the database.
I don't know what the GP meant by "pre-tapped," except, I suppose, that there might be legal precedent stating law enforcement has a right to request this data. If you're ever arrested, they can get the data off your phone, at which time it's the equivalent of having followed you around (even when they never did).
Or they could ask the cell phone companies for the exact same information that is stored in the phone (as they are keeping that same information on their servers).
Again, what? How could an app that's sitting on your desktop Mac at home know where you are when you're not at home? Clearly this doesn't seem to be an issue for you, but it certainly is for everybody else.
See above. The database of locations is not software accessible on the phone, only in the unencrypted backups on a regular computer. It's not an issue for me because I chose to encrypt the backups by clicking the check box.
It would be different, and if you don't see that you're blind. A person hired to follow you around actually has to follow you around. That costs time and money. This way, all the attorneys have to do is subpoena the information that they already know is on your phone. Second, an investigator that follows you around has to take the stand and give testimony against you, and your attorney has the right of cross-examination. "Did my client appear to be looking at the children? Which table was he sitting at, and which direction was he facing?" With automatically gathered location data, it merely has to be presented by the prosecuting attorney and, in the jury's eyes, it's up to you to shoot holes in this "factual, computerized data." That's a big, big difference.
You're right, they would have to pay a PI. Or they could put a tracking device on you. Or they could ask the cell phone company for the exact same data that is on the phone. If the government or someone with with sufficient resources wants to track you - they're probably gonna be able to track you.