Cuba does better than Vietnam by all measures. Education (literacy rate is 80% in Vietnam vs 100% in Cuba), healthcare, nominal GDP (2k in Vietnam vs 6.9k in Cuba per capita), Human Development Index etc.
Being pro-American (whatever that means) is not the holy grail or something like that. Besides, the notion that Cubans hate the US is just wrong.
Cuba has all the benefits of a European nation. They've had major Universities for many centuries. They've had one of the highest literacy rates in the region for most of their existence. They have a tiny population (11m). And most importantly, they universally speak Spanish.
Vietnam has more than 80 million people, in 54 major ethnic groups with more than 50 distinct languages spoken.
"By all measures..." No, not by all measures. By some statistics, sure. But Cuba is an oppressive police state. Sure, humans can live long, healthy, literate lives in captivity. Yet what value is literacy when the state regulates what you can read and what you can say?
Vietnam is arguably a lot less homogenous than Cuba with respect to disparate linguistic and cultural groups. There is value in preserving heterogeneity just as there are in metrics derived from a unified market (or state) economy.
Being pro-American (whatever that means) is not the holy grail or something like that. Besides, the notion that Cubans hate the US is just wrong.