It's not a tier - it is discretionary, and yes, often given to valued commercial partners or people who control very significant spend. I am sure some federal cabinet ministers have accepted it (but others avoid it like the plague). It does not have anything to do with actual miles flown.

I think there is also a distinction between having VIP status as part of the program and special treatment that is given to certain people flying - more in the high visibility category and those people will have people make the necessary arrangements for their trip (and don't need to flash a card).