Ask HN: Why is automatic translation still extremely bad?

We've seen much progress in AI, machine learning research and practical results. We've greatly increased the amount of data that can be handled effectively and the amount available to Google et al in the past 10-20 years. Yet, automatic translation (Google Translate) between others than a handful of similar languages is still extremely bad. Attempting to translate Arabic, Hungarian, even Swedish to English yields mostly gibberish. What's missing, what are the problems that haven't been solved and can't even be tackled with massive amounts of data (i.e. manual translation of phrases)?