I sincerely appreciate the desire to protect one’s privacy as much as the next person. The question often becomes what level of inconvenience and expense one is prepared to deal with in doing so.
It’s true MetroPCS and others offer prepaid cards (purchaseable with cash) that may be used to fund their services. Republic does not offer an equivalent to prepaid cards. If one wants or needs that level of privacy with their mobile phone service provider, perhaps using such a service rather than Republic makes more sense?
Finally, and for what it’s worth, one might argue attempting to hide one’s identity from Republic is a violation of Republic’s Terms and Conditions. Those Terms and Conditions are an agreement one voluntarily enters into as part of provision of service. References to “you” are all over the place in that document. While not expressly stated; it seems reasonable (to me) there’s an implied expectation that Republic know who “you” is.