Or with the 9€ Ticket in Germany?
Well, of course a ticket, that was limited to three months did not have a lasting effect on car usage. No one would sell their car and switch to public transport because of such a short, temporary price reduction. Even the follow up ticket (costing 49€ currently) is only guaranteed for a year at a time, then the government has to discuss funding again with the federal states. To have people switch from cars completely, it has to be a long term alternative.
But even if only some trips are now done with public transport instead of car, it is still an improvement.
I agree with you, that a good quality is also important, but I don’t think it will happen, if the financing for improving the quality has to be primarily via ticket pricing.
It’s mostly because you can have tickets that are not bound to a specific train. Aside from things like monthly tickets you can also have tickets for a single ride, which have a fixed start and end station, but you can take any train on the booked day. When you don’t know beforehand, which train you will take, you can still reserve a seat as soon as you decide (even just before the train leaves)