How are petro states able to maintain gasoline subsidies without black market export smuggling?
There has been rampant smuggling from Venezuela to Colombia - see links below. This is the basis for my question.

http://www.wsj.com/video/colombia-black-market-gas-trade-/BC14C5B7-69A0-4A0E-84B2-5377A7FDF79B.html

http://www.wsj.com/articles/venezuela-pays-price-for-smuggling-1402271308

http://www.wsj.com/articles/venezuela-to-reopen-colombia-border-1470962864