Does seem to be concentrated mainly in Scotland doesn't it?
Do they have different specifications for their network? Do network rail still specify their platform builds?
The rules governing tactile paving originate from the Technical Standard for Interoperability for Persons of Reduced Mobility (PRM TSI) - so it's from the EU.
The requirements are written in to UK Law as part of the Equalities Act.
The DfT have then produced their guidance in the form of the Accessible Stations Code of Practice.
Network Rail standards apply across the mainland network which includes England, Scotland and Wales.
In terms of platform build ( as opposed to tactile paving) this is also determined by TSI which determines height and offset required. This is also transcribed in to RSSB Guidelines and NR Standards.