@vadim yes, if you don't have a car and are deciding whether to purchase one or rely on the public transport, it makes sense to count total cost of ownership of the car. But if you already have one and you're only deciding if you want to leave it home and go by train or not, it makes sense to only count costs incurred by that particular ride, everything else is a sunk cost. IMO public transport should be attractive for families with cars, too.

@miroslavbucek TCO is definitely much more than 300 CZK, but once you already have the car it's a sunk cost which shouldn't be considered when you're deciding whether you go by car or leave it home. And if you count it, it actually motivates you to use the car even more because the more you drive it the lower the cost of ownership per km is.

If the car cost one million CZK and you don’t plan to drive one million kilometers—more likely around 250,000—then you need to add at least 4 CZK per kilometer to your costs.

@miroslavbucek Sure, but what I had in mind is a situation where a family already has a car (because most of them do) and they're deciding whether they want to go by car or use public transport. For that decision making it isn't longer relevant what they paid for the car beucase it's already been paid, a sunk cost. The decision won't increase or decrease the cost.
I know it isn't a fair comparison because the family can omit it as a sunk cost while the tickets have to cover amortization, but it's a decision families face all the time and if the public transport costs 7x more it will push the families into relying on their cars even more and increase individual transport with all its negative externalities.