King Drupada says 3 issues:
'One of low birth can never be the friend of one whose lineage is pure,
Nor can one who is not a car-warrior have a car-warrior for his friend.
one who is not a king cannot have a king as his friend.
Drupada was not talking about the low birth here. He was talking about 3 issue, ie., his status of being a King and Drona ...