Whilst the FFS might have a different opinion, from my experience, the UK interprets EU law to a much higher standard, particularly with regards to the Management of Health and Safety at Work Regulations, Provision and Use of Work Equipment Regulations and the Work at Height Regulations.
It's always interesting and useful to have a knowledgeable perspective from the IRA world.
However, we must distinguish between Industrial Rope Access and Caving. They are not the same things, and they will not be treated the same in a court of law.
You have a bunch of portentous phrases there in Serious Capital Letters, but notice the one word they all have in common: work. Caving is (generally) a sport or hobby, not work. Different standards and expectations will apply.
It's similar to legal liability when rendering first-aid. In a court of law, you will be judged according to both the context (e.g. casualty was in a hospital / casualty was in a cave) and your level of training (you are a doctor / you are a first-aider / you have no training at all).
Now a general comment about these Simple vs. Stop debates:
I would like to see less arguing about the device, and more emphasis on proper and safe training. I hope we can all agree that proper control
with the rope is the core skill, regardless of the device. But how often have you seen complete beginners abseiling over a bridge, or from the top of a hall? What happens if they get it wrong? They hurt themselves. This is not theoretical: I know of at least one case where it happened; the person was seriously injured and (big surprise) never came back.
Some people "get it" first time, but others don't. I think the very first abseils should be thoroughly protected. That means either a belay (for a longer abseil), or a very short abseil off a platform (max ~1--2 metres), preferably onto a crash mat.
These first abseils should either be on a Simple, or a Stop with the handle disengaged. That is the only way to be sure they "get it" and are not relying on the handle of the Stop (which is an extremely common issue). They must of course use a braking krab, and it's much easier to learn this from the beginning than trying to fix it later.
Personally I much prefer starting with very short abseils. Once they can control the abseil with the rope, we look at locking off and unlocking, making sure that it's done in a controlled manner (without letting go the rope or having a bunch of slack "jump out" when they unlock).
After this, I will teach them how to use the Stop correctly (unless it's clear they will be using a Simple when they go caving). This is a progression from the Simple. We are still near the ground.
We then move on to prusiking and changeovers, again max. ~2 metres off the ground. By the time they get any higher, they already have a complete set of skills. Staying close to the ground also builds confidence.
At this early stage, there should always be a simple way to get them off the rope, by bringing something along for them to stand on (maybe the same thing they stand on to start their abseil).
