It is also unclear what happens if someone doesn’t have ID when they show up to vote.

No it’s not really unclear at all if you actually look it up. The Secretary of State website run be each State has information about voting identification requirements and when and how provisional ballots work.

Exactly which forms of ID are acceptable varies however. That’s where the Voter ID laws that are an issue almost always require something like a State-issued ID that is not free to obtain. Which in practice means there is a required tax to be able to vote (poll taxes are clearly illegal) since you would be unable to vote for free if that was the only identification option. So States have alternative identification options.

Let’s take a real world example, in Arizona for instance (a Red/Purple state), here are the valid identification options:

When you arrive to vote at the polls on Election Day you will announce your name and place of residence to the election official and present one form of identification from List #1 or two different forms of identification from List #2 or 3.

List #1 - Sufficient Photo ID including name and address (One Required)

• Valid Arizona driver license
• Valid Arizona non-operating identification card
• Tribal enrollment card or other form of tribal identification
• Valid United States federal, state, or local government-issued identification

Please note: Members of federally-recognized tribes are not required to have an address or photo on their tribal identification in order to cast a provisional ballot.

List #2 - Sufficient ID without a photograph that bears the name and address (Two Required)

• Utility bill of the elector that is dated within 90 days of the date of the election. A utility bill may be for electric, gas, water, solid waste, sewer, telephone, cellular phone, or cable television
• Bank or credit union statement that is dated within 90 days of the date of the election
• Valid Arizona Vehicle Registration
• Indian census card
• Property tax statement of the elector’s residence
• Tribal enrollment card or other form of tribal identification
• Arizona vehicle insurance card
• Recorder’s Certificate
• Valid United States federal, state, or local government-issued identification, including a voter registration card issued by the County Recorder
• Any mailing to the elector marked “Official Election Material”

List #3 - Mix & Match from Lists #1 & #2 (Two Required)

• Any valid photo identification from List 1 in which the address does not reasonably match the precinct register accompanied by a non-photo identification from List 2 in which the address does reasonably match the precinct register
• U.S. Passport without address and one valid item from List 2
• U.S. Military identification without address and one valid item from List 2

And then if you need a provisional ballot, here are those requirements:

A provisional ballot may be issued to a voter if

• Voter was sent an early ballot
• Voter name does not appear on the signature roster
• Voter is in inactive status
• Voter changed their name
• Voter moved to a new address within the county but did not update their voter registration

Conditional Provisional Ballot
A voter will be issued a conditional provisional ballot if they did not provide acceptable proof of identity to poll workers. In order for their conditional provisional ballot to be counted, the voter must provide proof of identity to the County Recorder by 5:00 pm on:

• The 5th business day following a general election that includes an election for a federal office, or
• The 3rd business day following any election other than a general election.

No person should be turned away from the polls without being offered a provisional ballot. Provisional ballots won’t be counted until the county verifies that the voter is in fact registered and eligible to vote. A voter must also be in the correct precinct for their provisional ballot to count if their county does not use vote centers.

https://azsos.gov/elections/voters/voting-elections

Note that all of these are just for identification on the voting day, tto prove you are the person who’s name you’re voting as. States require you to register before the elections… and that is where things like citizenship and voting eligibility are verified ahead of time to even get you on the roster at your voting location.

And none of that addresses the reduction and removal of polling locations, long lines, little to no early voting options, etc. that are all designed to remove your ability to even get a chance to vote at all.