Tanks also only work against an unprepared enemy, but I think many will agree that tanks can still do lots of damage, even given the prevalence of armor-piercing munitions and anti-tank weaponry.

In practice, how many people are going to have RFID jammers, and how many of those will reliably work? I'm guessing that that'd be close to zero. Related, Psycho Pass is an interesting anime which goes into the issue of "smart guns" and the subversion of their safeguards. It's also a damn interesting series.