The thing you're not mentioning is that these doctors don't live in Cuba. They live in capitalist countries in which the government doesn't (even try to) provide X, Y, and Z.
Sure, the doctors got a free education, and that's worth a lot. But at some point they'll have paid off the value of that education and after that point, they're still being taxed at some very high rate and they're seeing no benefit from those taxes because they live in Brazil. Seems like exploitation to me.
I wonder if other countries (US, France, England...) students would see things like this Cuban doctor if they had full medical education for free. Would they think relatively to the tuition system ? would they say that being able to cure people is so worthy they'd do it for free.
In other words, this article is trying to attack Cuba for what it did right as a communist country, not for what it did wrong. If this were the worst that came out from Cuba, then it would be pretty close to perfect.