Tax is Statutory obligation every citizen pays. And it has some fairness. The taxes are levied for welfare activities.
Here a person travelling opposite you might have paid double the amount you paid. There is no rationality. Lalooji had introduced SMB to augment the income of railways. and this was vehemently opposed in south India, with threat of going to court, and then it was removed 'graciously'. Same way flexifare is a loot by Govt not having any rationale. If every train has same fare structure it can be understood. But this Flexi Fare is in fact unfair. Like private schools charging 'donation' for offering management seats.