The idea behind "swapping SIMs" to avoid being tracked assumes that the phone itself can't be identified and tracked (regardless of the SIM card in it). Once on

The idea behind "swapping SIMs" to avoid being tracked assumes that the phone itself can't be identified and tracked (regardless of the SIM card in it). Once one of your SIM cards can be identified as belonging to you (maybe you break down and call a relative), it can be linked to the phone. If the phone can be tracked, then all of the other SIM cards that you use with it can be linked together, regardless of the whether or not the original purchase of the phone or SIM cards can be linked to you (cash vs. card).