https://en.wikipedia.org/wiki/International_Fairtrade_Certif...
As with any such program, if it is implementing effectively then some companies will chafe at the requirements and try to develop their own fair trade program more to their liking.
Of course there's no logo saying the chocolate is made with child slavery, I hope you didn't mean to be snarky here.
There are initiatives to try to alleviate the problem, the only example I have in mind right now is Tony's Chocolonely (which explains the problem and their solution on their website) but I'm sure others could come up with other initiatives.
The trends from top companies of chocolate is that they try to do as little as possible to alleviate the problem of child slavery in chocolate production.
...?
Quality labels are a thing, why couldn't an independent NGO overwatch the production?
Expensive because you need to pay an inspector (ideally multiple to avoid corruption) to visit these farms.
Easy to bypass because the kids aren't working the fields all the time and there's plenty of warning an inspector is coming.
And the enforcement mechanism is you don't get the label... But like there's plenty of buyers for slave chocolate so that mostly means a minor hit on income.
NGO inspectors are better than nothing, but we should be clear eyed in how much they can solve. The only way to significantly reduce slave labor is harsh penalties on companies that trade in slave goods. That was pretty much the only thing that collapsed the ivory market.