Bob is correct in his understanding of the intent of the table. Based upon the assumptions made to calculate the table, when a conductor is loaded to the tabulated ampacity it should just reach the temperature rating of its insulation.
The big reason that conductors run cooler than this is that there is better thermal conductivity away from the conductors than the table assumes. With better cooling than table 310.16 assumes, the equilibrium conductor temperature will be lower than the table suggests.
Back to the original post, I wonder if 75C only terminations have limitations to protect the wire from device heat in addition to the temperature ratings to protect the device from wire heat? Similar to the instructions on some lighting fixtures that require 90C rated wire.
-Jon
