Face recognition and plate scanning are orders of magnitude more complex than knives, which have been around for ~1,400,000 years. Kids can (and do) make knives

Face recognition and plate scanning are orders of magnitude more complex than knives, which have been around for ~1,400,000 years. Kids can (and do) make knives with random material they find. Effectively 0% of adults can make face recognition or plate scanning systems. Also laws do work in these scenarios: look at the difference between US and Israeli security practices and you'll see dramatically different laws in effect.