I agree with you, I don't think this graphic (or at least the underlying data) is very useful as an indicator of international military relationships. Of course it doesn't claim to be either.
As a single example, I recently decided that I don't know enough about US-Israel relations and started reading more on the topic. A report[1] I found linked from Wikipedia states that the US has provided Israel with $121 billion dollars (non-inflation-adjusted) since WWII, almost all of it military aid. The graphic shows $35 million in exports to Israel for 2013, the report lists $2.9 billion dollars in military aid in 2013.
If those figures didn't make it onto the graphic, there are probably many others which also don't.
As a single example, I recently decided that I don't know enough about US-Israel relations and started reading more on the topic. A report[1] I found linked from Wikipedia states that the US has provided Israel with $121 billion dollars (non-inflation-adjusted) since WWII, almost all of it military aid. The graphic shows $35 million in exports to Israel for 2013, the report lists $2.9 billion dollars in military aid in 2013.
If those figures didn't make it onto the graphic, there are probably many others which also don't.
[1] http://www.fas.org/sgp/crs/mideast/RL33222.pdf