Incidentally, we had someone with an ankle monitoring bracelet here today at the office, first time we ever encounter that. Apparently, the wearer is supposed to request special permission to leave the assigned areas, like coming to our office, way in advance (he lives about 30 miles away from his home). Perhaps her grocery store is in the vicinity (same shopping mall) as the nail place? From what I have read, the justice system is overwhelmed as it is and unless there's a red flag of someone leaving their community, they won't make an issue out of someone hanging out in their area for a little longer than the allotted time.
There is also another type of monitor (SCRAM bracelet) that only checks for drug and alcohol consumption, so it is possible that she had that type, versus the kind that checks for your location. By the way, parents can now purchase these ankle monitors to monitor their teens' whereabouts, so maybe it wasn't even a court-mandated ankle monitor, but one that a parent bought to keep control over their unruly teen, and they don't mind the nail salon, as long as she's not at the underage bar getting drunk or going to her boyfriend Mikey's home: https://reason.com/2018/12/11/teen-ankle-monitor-florida-...