How are petro states able to maintain gasoline subsidies without black market export smuggling? I don't understand how petro states can have crazy low gasoline prices without smugglers exporting the gasoline and selling it elsewhere.

For example, in Venezuela the domestic price of gasoline is about 5 cents per gallon (compared to the current US retail price of around $2.10 per gallon). In other words, the US retail price is about 40 times the Venezuelan price. That is a pretty big incentive for a smuggler. There are other countries which have similar subsidized prices.

How does Venezuela prevent smugglers from just loading up trucks with gasoline and exporting it? They don't even have to ship it out of Venezuela. They could truck it across the border into one of the neighboring countries and sell it there or export it from the neighbor. Venezuela must have some mechanism for controlling who is receiving the cheap gas and preventing them from exporting it, what is it?

As a second question along the same lines, how do they prevent people from converting the oil into a different product and then exporting that product. So, for example, oil can be converted into polypropylene pellets. A person could take the (virtually) free oil, convert it into polypropylene and then export the polypropylene. How do they prevent this from happening?
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