Because it costs money to get a photo id. That's how it can be considered equivalent to a poll tax.
Only if it's not funded by taxpayers, which is a very small price to pay, considering the fraud alternative that brings the socialist/liberals into the legislation of entitlements programs.
I'd GLADLY pay my share in taxes for voter ID costs, compared to how many people I support now via the tax-me-through-the-nose entitlements programs the liberals have saddled us with now.....