Some things to keep in mind here....
Just about everyone outside of the barrens is broadcasting an AID, simply cause everyone is online ALL the time.... That is why "the new matrix is uncrashable", it is made up of everyone and everything that can broadcast, broadcasting! Heck, in some parts of some towns, it's a crime to NOT be broadcasting!
Now, does that make it easy to track someone? you bet it does! IF (and this is a big one) you have the time and effort to sort through the THOUSANDS (if not tens of thousands!!) of AIDs that connected to a given site simply by passing close to it, and that person is not trying to actively evade your attempts to track them! Now, 99% of the population give their AID no second thought, it's a part of them as their SIN is, and they take it for granted.... But shadow professionals (or just professional criminals in general) take their AID very seriously as it can lead a reprisal/retrieval team to their front door!
However, tracking a AID across the matrix is not something that is done in seconds... or minutes for that matter! it takes hours if you are lucky.... Simply cause of volume you have to go through.... All the static AIDs (like vending machines, shop stands, traffic controllers, and all the rest.) and all the mobile AIDS (people, pets, vehicles, etc). Sure, a search bot or sprite can look through this list faster then a person could, but, can you imagine how many entries a vending machine sitting on the corner of the street would have logged in just 10 minutes? Every person walking by it, every pet, car and truck, every supplier checking inventories..... all of those are logged. And then all you know, is that at this particular time, that AID was in contact with the machine.... now you have to move onto the NEXT machine to setup a trace.... That's where the time comes in.....