I had the keyless entry on a 2005 Acura RL I had and it worked perfectly during my ownership. The RL had sensors on all four doors so I could open any door using the keyless entry. This was a huge bonus as I usually had something in my hand that needed to be loaded in to the rear seat.
I support the keyless entry feature on the RDX except for one issue that I am experiencing. The RDX does not have sensorson the rears door and when I leave work each day, I have to open the doors using the sensor in the front handle. All of my cars have the sensors on all doors to allow access from any door.
Hopefully Acura will correct this issue with the 2015 model. This is probably the biggest issue I have with my RDX but overall I am very satisfied with it so far.

 

I recall being told when I picked up the car there's a setting with the rear locks on the customised settings. Probably a long shot but there may be an option in there.

 

All you have to do is touch the inside of the front door handle 1st and then open the rear door. You cannot compare an RDX to an RL. The RL will just have additional niceties because of its price.

 

This is a very good solution.

The 2005 RL does not have sensors on the rear outside door handles (only the front 2 doors like the RDX). You can set the RL and RDX to unlock all doors when the drivers door handle is grabbed (this is done through the MID options). The passenger front door handle will unlock all doors no matter what setting you have set on the MID.

The new RLX and 2014 MDX with the tech package and above are the only 2 Acura models right now that have sensors on the rear doors.