Dunkerque isn't exactly a tourist location! At least for French people. It's in the north of the north so it has worse weather than most places (the North is notorious for its rain and cold compared to other places, everything is grey.). Every French person will tend to go south to their hometown when going on vacation.
> it will be money pit
This is not a given at all. You have to consider the cost of enforcing the payment system. If transport is free you don't have to maintain the turnstiles and gates, employ verification agents, create cards, print tickets, etc. It's not clear at all that fares are covering this cost by themselves. Public transport is already greatly subsidized and already free or cheap for large parts of the population (elderly, disabled, unemployed, students, children).
> it will be money pit
This is not a given at all. You have to consider the cost of enforcing the payment system. If transport is free you don't have to maintain the turnstiles and gates, employ verification agents, create cards, print tickets, etc. It's not clear at all that fares are covering this cost by themselves. Public transport is already greatly subsidized and already free or cheap for large parts of the population (elderly, disabled, unemployed, students, children).