Showing id to vote therefore won't improve things in any meaningful way. While the negatives are easy -- what do you do if you lost your wallet the day before voting day and have no other accepted form of id?
If there are no benefits, why have it at all?
By comparison, from what I read, lots of people cheat the vaccine card system, so an id that helps verify that the vaccine card is indeed for the person presenting the card. The benefits are supposed to be the reduction of the infection rate, the ability to have an alternative to having business shut down either by order, or because of consumer reluctance.
Maybe you disagree with the conclusion of that cost-benefit analysis, but it's far more substantial than the benefits of having voter id.
> Why aren't you counting any of passport books, passport cards, or REAL ID-compliant IDs (which are finally available nationwide) as national IDs
Because it's a de facto, ad hoc, and incomplete system that isn't comparable to at least some of those countries.
In some of those countries which require voter id, you can get a valid id from your local police station, or from your bank, or the tax office. While the US ones seems to be centered around a much smaller number of DMV offices.
In Belgium, everyone is supposed to have an id. In the US, something like 9% of the population doesn't have an id which would be acceptable for voting. (Eg, don't drive because of age, illness, poverty, or live in a place with good mass transit.)
As a reminder, double voting (voting in more than one district) is also a form of voter fraud. Though, oddly, it isn't always illegal! - https://www.ncsl.org/research/elections-and-campaigns/double... . Even when illegal, it is NOT solved by presenting photo id. One solution that does solve it is to set up a nation-wide registry of where people live, with the legal requirement that if you move you inform the authorities. That's what some of these countries do, as part of their national ID system. This also updates your voting location.
And those are reasons why the US system isn't easily comparable to an actual national ID system, as well as helping highlight how the emphasis on in-person impersonation voter fraud over other forms of voter fraud is artificial.
(As a reminder, four people from The Villages, Sumpter Counter, FL have been arrested for suspicion of casting multiple ballots in the 2020 selection - https://www.msn.com/en-us/news/crime/resident-of-the-village... - so it's probably more common than in-person impersonation. ... but I'm having a tough time tracking down those numbers!)
In any case, these sorts of voter fraud are paltry compared to wholesale gerrymandering practices.