In a democracy all citizens have the right to vote.
In some democracies, such as the USA, each citizen needs a photo ID in order to vote.
The economic cost of a photo ID is negligible or affordable for most citizens in the USA. By implication, the economic cost of a photo ID is unaffordable for a small but significant number of citizens.
The economic cost of a photo ID is a barrier to voting.
The right to vote has an economical value.
An 18 year old man from a very poor family, who has knuckled down through school, cannot afford a photo ID.
He cannot vote.
The state has a moral obligation to ensure the rights of its people. The state should ensure all of its citizens are able to vote.