The thing is, I think that by the time the pilots should start to be "tested", they would be ready to begin touch and goes on an actual carrier to start to build up their confidence, whereas an angled land simulated runway without any tarmac beyond the simulated flight deck would offer little additional benefit to a pilot. It actually present more risks to the pilot and the aircraft, as doing a bolter on land at the end of a runway is much riskier than doing a bolter on an aircraft carrier when an overshoot of the carrier flight deck means there is nothing but air around them (and ocean many meters below such that it can be dismissed as a dangerous factor) so they can perform a safe recovery easier (and more importantly, most poor recoveries would not result in danger to the aircraft), rather than solid hard ground which may be directly on the same level as the simulated runway or at best a few meters lower, where even slightly poor recoveries can result in crashing the plane into the ground.
In other words, I actually think it's safer for pilots to mess up on a carrier than on a land based simulation at the end of a runway.
Given that the Shore Based Test Facilities for other navies with similar infrastructure all have simulated carrier runways in the middle of (and parallel to) main runways, I think there must be a reason why those are the chosen preferences... and I think the limited benefit and the great risk from having a runway at the end of a runway on land probably explains it.
Firstly, just because there isn't tarmac doesn't mean the plane will suddenly be destroyed if any of it wheels touches anything other than the simulated carrier.
As I said before, the land around, and especially in front the simulated carrier is almost certain to have been treated to allow planes to land safely on. That is also why the simulated carrier is a little offset compared to the runway, so that anyone attempting to line up and land on the angled deck would actually end up following the runway.
Secondly, as you said, the pilots should almost to ready to start landing on a real carrier by the time they are progressed to this simulator, so I seriously doubt any of them would miss the target by such a wide margin as to potentially barely, or not even touch the carrier deck (and even in such extreme cases, they should be trained well enough to know they should be waving off rather than trying to press on with a landing if they are hopelessly out of position).
But if someone does manage to mess it up so spectacularly, it would reinforce the benefit of this simulator over the real thing.
With the simulator, you are going to have maybe another several hundred metres of runway grade prepared ground for the plane to use to gain speed for lift off again.
On a carrier, you would be in the drink if you messed up so badly.
In effect, the biggest difference between the simulator and the ones in the middle of the runway would be the colour of the runway in front of the simulator. You will have pretty much the same margins for error (although the instructors will probably not tell the pilots that to help them get the most out if it).
But the time the pilots are trying this, their technical skills should be flawless, so its mostly the mental and psychological training they will be focusing on for this.
As for why other navies don't do this, well that is because other navies are either far more advanced in terms of their carrier operational training and training equipment, or don't have the budget for such luxuries.
For the likes of the USN and French navy, they already have a pool of well trained and experienced carrier pilots with dedicated twin seat trainers.
As far as I am aware, USN greenhorns experience their first few traps in trainers with an experienced veteran pilot in the back seat. My memory is a little fuzzy here so I may be wrong, but I remember that for the first few traps, they are pretty much just along for the ride, with the instructor doing the landing to give them a first taste of what it feels like to land on a carrier.
The PLAN cannot do this yet, so it makes sense for them to give their pilots additional land based training, since when they try landing on a carrier for the first time, they will be riding solo with no one on hand to help or take over if things get too tough.
