Tesla may pride itself on making the world a better place through eco-friendly electric cars, but it's not immune to ethical concerns. Mercury News has discovered that at least one of Tesla's contractors has been using sub-contracted, low-paid labor (as little as $5 per hour) from eastern Europe to work on the automaker's facilities. The partner companies have avoided offering overtime pay and even compensation for injuries -- one man is suing his employers after he fell three stories while working on a Tesla paint plant in Fremont. The practices let those contractors finish crucial factory...