In March of 2019, the Dutch regulator compelled Vodafone to publish its wholesale access rates or face a one million Euro fine.
The regulator in Botswana (BOCRA) publishes a public rate card for access to the national fibre optic backbone. Granted this is a state-owned network which removes the complication of negotiating with the private sector but even if we just succeeded with state-owned networks, this would be a big leap forward.
In West Africa thanks to a directive in 2006 from UEMOA, the West African regional economic community established a practice of publishing backhaul and interconnection pricing.