In my opinion it is still not obvious enough. We live in a world where there are literally hundreds of T&Cs you have to read to just function in society, and people just don't do that.
There is empirical and legal evidence to support this vibe, FWIW. Not only are there various studies pointing to the fact that no-one reads T&Cs (in one study, 98% of participants 'agreed' to give their first-born children to a social networking site*), but a recent study specifically found that people are more likely to blindly accept terms the more the presentation of those terms resembles website-style T&Cs.** This does lend weight to your suggestion that—if they want people to obey a rule—they shouldn't present it via T&Cs.
Indeed, the courts have found that onerous terms buried in the fine print are not enforceable, as anything particularly unfavorable or distinctive must be brought to the customer's attention in order to count as part of the contract—suggesting that the position in law is also, to a point, that no-one reads the T&Cs, and that hiding onerous rules in there is unfair. Although, I'm far from a lawyer, and there's a good chance that Railcard T&Cs aren't anywhere near the threshold!
* Jonathan Obar and Anne Oeldorf-Hirsch (2020), "The biggest lie on the Internet: ignoring the privacy policies and terms of service policies of social networking services", Information, Communication & Society, 23:1, 128-147
** Rainer Böhme and Stefan Köpsell (2010), "Trained to accept? a field experiment on consent dialogs", Proceedings of the SIGCHI Conference on Human Factors in Computing Systems, 2403–2406.