Votebans is effective. If the kid annoys, almost everyone vote yes. For example: From 12 players votes is: 2-4 votes are no and other votes are yes.
Well, not from my experiences.
Either way, I think the BEST solution for this problem is for people to stop bitching about it and just mute kids on their own. EVERYONE knows that there is a "Mute players" option in your menu when you press escape. It's TWO clicks of your mouse. It takes more work to type out "STFU LITTLE KID" or "GTFO TURN UR MIC OFF DUMBASS" than to mute the player.