stingrays just force the device down to 2G and capture that
I know my Canadian SIM card somehow hides US providers from network scans, possibly with some geo or if/then rules (but visible from my EU SIM that tries its darnedest to latch onto the US networks and avoid the Canadian ones at all costs)
The way I see it, seems law enforcement agencies using stingrays have a vested interesting in seeing 2G alive and well.