Yes they're local, but its not like there's a limit to how many local charities there can be in the world.
Operating at a huge scale requires you to lump people together into groups and make assumptions about who they are and what they deserve, as you've done in your example. To me that sounds antithetical to the concept of charity. And even with the best intentions, if you mess up, you're messing up a huge scale.
Charity just means helping someone. Do you think no one in Chad needs or is offering help? And if you don't know anyone in Chad who's in need of charity then...why do you want to do charity in Chad?
It seems that our notion of charity has been warped in such a way that it somehow doesn't count unless it's some enormous large-scale mission carried about by Charity, Inc for the benefit of some group of people far away. It's all very abstract, and that just creates room for fraud or exploitation.
Paying off a local person's debts or putting their child through college will probably be far more impactful and meaningful than sending your money off to some giant organization.
And even the poorest parts of the US are doing much better than a lot of poor countries in Africa and Asia.