In a lot of countries you are not allowed to just record private conversations with listening devices (and it is not happening as a mass phenomenon), so clearly we can legislate successfully against use of technology.
What would prevent me from walking around the street or in semi-public places recording non-stop on my phone? Heck, I could have a few phones in my pockets!
Along the same lines: what would prevent you from using a knife to kill someone and hoping/attempting to make sure that no one notices?
Indeed, even though murder is illegal, it still happens. But the law is there to codify that murder is heavily frowned upon. Places where legislation were absent of the law isn't sufficiently effective enforced, tend to have more random violence.