Major League Baseball is a $10 billion/year industry - its revenues have increased in each the last 15 seasons and Commissioner Rob Manfred has made $15 billion a goal in the near future - and it has been working its ass off for years to be handed the right to ignore basic labour laws (which remain grossly inadequate for workers, but that's another story).
According to this extremely interesting post at Camden Depot, the Yankees pay roughly 0.33% of their annual revenue on minor league salaries. That is likely typically of all teams, as even the Rays pay only 0.