In order to pay for the energy, we need to pay for the ticket. So I think it's fair to pay since we all pay for food and the stores that sell things in the city.

Because otherwise the subway would always be full and then the other public transports would not use anything.

The cost of public transport is very high, because if we paid the actual cost of the ticket, it would be worth more than double than currently, thus, the 20 euros for the 10 trips and 3.50 euros for the single ticket.

We also pay to have better conditions in the metro.

If you do not pay for the subway ticket, it would be illegal and you should also pay 100 euros, which would be the fine. It is always better to pay for a tube ticket than pay for a fine.

We all prefer to pay for the ticket and thus we will have better conditions. It would also be good idea to make small children from 5 to 16 years old pay the T-16 and it turns out to be cheaper.