It was my guess that this would be the reason to give this practice a pass. Are the same dynamics in play in regards to foreign basketball players?
Foreign born players are eligible for the NBA draft, but there are some weird wrinkles in terms of player development.
NCAA rules are much more strict and heavy on college players regarding practise time, and coaching. European rules are more conducive to gymrats and workaholics.
When European teams get these players, they are generally more polished then NBA players of the same age. However, drafting them, is a risk and gamble as they are generally already on a european professional teams. You can draft them, but you need a myriad to get them (though obviously its quite possible).
The NBA doesn't do academy's on their own, but provides assistance (league wise, not team wise) to other countries.