The airport is responsible for the signage, don't blame the rental agency. As for the length of time, there have been some recent increase of traffic to/from ORD and the city is trying to do its best to minimize it, unfortunately it appears to me that they have not been able to find a good way to handle this. Uber/1Lyft drivers have reported that it takes them almost 20 minutes to get to the terminal once they leave the TNP lot to pick up a passenger.