The system is called RARS, the quotas are set by the train operating companies and there's no transparency whatsoever as to how many tickets there are available

The system is called RARS, the quotas are set by the train operating companies and there's no transparency whatsoever as to how many tickets there are available per train service/journey segment at each price point (commercially sensitive). The most you'll get is a "there's 2 tickets left", I think for all n <= 9 Advance fare tiers are also not regulated by the Govt fares increase cap, so the operators can charge what they like.