I still stick to my observation that Brits are not particularly obedient or rule-loving as such, but we HATE to draw attention to ourselves, as a rule. (Obviously individuals can be an exception!)
So a lot of what OP is citing as "obedience" is actually just avoiding standing out.
If following a rule will result in not standing out, then people will generally be obedient. If breaking the expected rule will bring unwanted attention to the person, then people are even more likely to stick to it. This is probably why the two things look the same, because the British "don't gain unwanted attention" culture is used in the enforcement of rules - this is possibly why we have so much CCTV compared with other places, because the CCTV is a silent indicator of "someone might come and call you out for this later".
If people will not notice or care, then people will be perfectly happy to break rules (or not) based on what suits them at the time. Such as, for example, crossing the road against a red light if it's safe to do so, parking illegally, dropping litter when nobody is looking, calling in sick to work when not actually sick, bringing your own sweets into the cinema, whatever.
It would be interesting to see how British people respond when there is a stated rule that would cause this to be broken, ie, the rule is to alert a staff member in XYZ situation, but it's possible to just ignore this and not notify anybody, and nobody is likely to come and find them later and ask why they did not do this.
I bet the majority of British people would slink away and pretend they were never in the situation in the first place or pretend that they had not noticed, in order to avoid having to attract unwanted attention, rather than follow the rule.
You can see this illustrated quite clearly in the example of somebody being disappointed when they have bought a train ticket but neither station they used had barriers and no conductor was on the train. This disappointment would simply never occur to a German, German trains have no barriers and there are very rarely ticket checks on normal public transport like trams/buses. The vast majority of people buy a ticket every single journey and do not consider it a waste if it does not get checked. I have probably been checked around 1-2% of the journeys I have made on local public transport in Germany.