Echoing what other commenters are saying. Depression takes many forms, and some of them allow you to still function. Just like some people can be a high functioning alcoholic, some people can hold down a job and achieve high levels of professional success while everything else in their life is crumbling to their depression.
There's also like 5 classes of antidepressant drugs, and several more that don't fall into a specific class. Each class has several options. If the first one doesn't work for you, that doesn't mean the next wont. The biological causes of depression aren't well understood and it's trial and error to find one that works for you. I would encourage people who are depressed to talk with their doctor, and find a medication that works for them. And don't be afraid to tell your doctor one isn't working, they won't be surprised.
Depression isn't one size fits all, and the meds for it aren't either.
There's also like 5 classes of antidepressant drugs, and several more that don't fall into a specific class. Each class has several options. If the first one doesn't work for you, that doesn't mean the next wont. The biological causes of depression aren't well understood and it's trial and error to find one that works for you. I would encourage people who are depressed to talk with their doctor, and find a medication that works for them. And don't be afraid to tell your doctor one isn't working, they won't be surprised.
Depression isn't one size fits all, and the meds for it aren't either.