For all we know, being Vegas, these people were too drunk and passed out. A valet cannot legally withhold the keys from someone even if they believe they are too drunk to operate a vehicle, so perhaps instead of letting them pass out on the lobby couches, they should have sent them on their merry way with keys in hand or to stumble the streets in front of impatient cabs and drivers... whatever it takes to maintain the integrity of a $100-200/night room (I went to school and maintain a residence in Vegas, so understand the offstanding circumstances of the city all too well).

But since the OP seems to suggest that it's not fair some get equivalent benefits for less, perhaps next time I'm staying in a hotel (oh wait, right now), I'll troll the hallway looking for folios to scout out the cheapest corporate rate and then complain to the front desk that I'm paying more than Person X for the same services