Every few years I rent a Toyota Prius when I’m on one of my trips, and the most recent trip was one of them. The Prius is a marvel of engineering, showing what is really possible when you choose a Hybrid Power-plant as the overall design center. Sure there are other compromises, like at best modest performance, but the Prius is comfortable, quiet, and roomy for a car that gets 45+ MPG. However, this Prius demonstrates an annoying failure on Toyota’s part.
Apparently in Japan men must not open the passenger door for their aging mother (or their wife or girlfriend). Because if they did then Toyota’s keyless entry system would include sensors in the passenger-side door handle as well as in the driver-side. So if you walk up the driver’s side door and grab the handle it unlocks, and if you touch the right spot on the handle it locks. But if you walk up to the passenger door and grab the handle nothing happens, and you have to fumble around for the key fob. Ditto to lock. This is extremely frustrating since you either get used to keyless entry or you get used to pulling out the key fob and pressing buttons. To go back and forth between the modes is a pain.
There are other problems with the design too. If you touch the lock button on the driver door handle before the passenger closes the door then the car just howls at you until the door is finally closed. This drives the (slow-moving) passenger crazy because it is as if the car is trying to rush them. Is that any way to treat your elders? Other keyless entry systems I’ve experienced handle this the other way, simply holding off on the usual locked beep until all doors have been closed.
What a Program Manager would do is write out all the scenarios and make sure that they’d solved the problem for the key ones. So either Toyota doesn’t feel that the courtesy of opening the door for a loved one is a key scenario, or they didn’t have a Program Manager think through the scenarios. I bet someone in marketing said “we need a keyless entry system” and the “lock engineer” just threw something together. At least that’s how their implementation comes across.
Hal's (Im)Perfect Vision 
I agree that keyless entry system is a mess. It is perhaps a symptom of the problems at Toyota that caused it to have all those safety recalls a few years ago.
It reminds me of the design issue with the remote locking system on my Acura. You can’t lock the doors with the key fob until all the doors are closed. This means that if I have enough things in the back seat that it takes two hands to carry, I have to take the items out of the car, put them on the ground, close the door, find my keyfob, lock the doors, and pick everything up off the ground. It’s even worse if I only have one or more items and it’s raining. I have the choice of either putting the item(s) down in the rain or putting the umbrella down in the rain while I lock the door with the other. Either I can stay dry or my item(s) can stay dry, but not both.
BTW I just read your other BMW post – and I can say that BMW has it perfect on their keyless entry. You touch the passenger side handle – it unlocks all the doors.