The Netherlands have implemented unlimited off-peak rail travel for €49/month:

<https://www.ns.nl/en/season-tickets/dal-vrij>

HN discussion 4 days ago: <https://news.ycombinator.com/item?id=48543872>

Given that many commuter-rail (and frankly, other) transport systems operate well below capacity during off-peak times and in counterflow directions, such pricing could well increase ridership and revenue.

This only is an attractive offer if you don't commute by rail & the country/ticket area is small enough to make avoidance of the peak hours feasible.