@Delphinna
Passing the test is pure luck. You’re relying on nobody cutting you up, nobody stepping off the pavement in front of you, nobody beeping at you, not encountering any hazards on the road, the examiner choosing a route with clear signs and markings and not much traffic, etc. You just have to keep attempting it until you hit lucky.
As an ADI I can confidently state this is nonsense.
Someone cutting you up and not because you have done something incorrect yourself, no problem if you deal with it safely
Someone stepping off the pavement - no problem if you react to it safely.
People beeping at you - no problem if you haven't done something incorrect to provoke this action.
Hazards on the road - just deal with them appropriately.
If signs and markings are not clear or visible, the examiner will give you guidance.
I have sat in the back in close to 700 tests, and examiners are remarkably consistent in how they apply their system of weighing faults. I have, on very rare occasions, seen things given as serious faults where I have felt that many DEs would give a driving fault. I have, much more frequently, seen what I felt was a serious fault be marked as a driving fault.
In a sense there is an element of luck in a driving test - in some ways quite a considerable one. Most people sitting a cat B are very inexperienced (not always though - people with lots of experience do take tests for various reasons) - as such the fewer complex situations you encounter the better as this is typically where tests are failed. But a well trained pupil who is in control of both their car and themselves should have a very good chance of dealing with these situations.
OP - if it was a following distance fault, then you almost certainly were not told that it was a 1 car length gap instead of 2. It was a 1 second gap instead of a 2 second gap. We measure following distance in terms of time rather than absolute distance so that it makes sense at all speeds. You would have had to be too close for quite a prolonged period of time for the fault to be recorded, or for it to have led to significant risk if it was only for a short time. I cannot emphasise enough the importance of space when driving. It gives you time to react, it gives you the opportunity to see further ahead and this is what keeps you safe - you cannot crash into air...