Yes, probably because it's a pair tech for them. 

The roman definitely used defensive ditches around fortified camps.   I don't think you could easily bring a ram to it.  I would see a point for such tech with some civs.  Then there is always the risk to make the roman too good if we give them everything the romans did

Maurya has 2 tech (  a choice)

Ofc cart has wicker baskets.   In their case it's paired with Ahimsa, I guess that's why it's there.

I just try with carthage, no exist 

@Dakara, the tech exists for everyone, not just Mauryans. That's why it's not a tech specific to them. Hence, it's a bug in the UI.