Just a food for thought... is it a government conspiracy-type theory? Or simple economics?

Ford and GM both offer light duty diesel vehicles across the globe, other manufacturers probably do too. It seems mysterious how Mahindra is being tripped up by the EPA with their smaller, lighter trucks and have been for quite some time. 

Any other ideas out there? Or ideas when we can expect to see a diesel Ranger in the US? Or a diesel Canyon? Heck, even a diesel Ridgeline would be great!