The cost of Luxembourg's free public transport plan

One inference here I disagree with:

One unexpected downside emerged in a study of the switch in Tallinn. The average trip length dropped by 10%, suggesting people were using public transport to replace trips they might otherwise have taken on foot or by bike, rather than in their cars.

Ticket pricing often makes it expensive to take multiple short trips, so users of paid public transport are skewed towards those taking single longer journeys (e.g. commuting nonstop). Making public transport free enables it for those who need to make multiple shorter trips - for example women with part-time jobs on top of childcare.

Another possible change with the free public transport is that it enables commuters to break their journey as they wish; I myself often stop off at a particular shop on the way home for groceries - but this is only practical because my prepaid bus pass allows unlimited journeys. If I was paying for each journey separately, I would stay on the bus all the way home and miss out on my preferred shop.