A friend of mine still sends large packages of blue jeans to relatives in Spain, so I believe there is still a big price difference.
Probably. There will always be grey market goods as long as manufacturers put quotas on domestic customers while other countries have higher taxes and regulations - and if there are shortages. Hard to imagine that Levis had production issues. Probably more a question of the distribution network being less efficient over there than over here due to multiple factors such as cost of transit, cost of labor/regulations, import duties, and mark-ups by intermediaries in the distribution chain.
Cheaper to get 2 large suitcases, fill them with jeans, and take a cheap charter flight. Or, pay someone to bring a couple of suitcases with them.