Maybe you mean where in bill does it say a US photo ID is required.
I think your are correct, I don't believe such a requirement exists in the bill itself and that's a big part of the article. Because the law doesn't require this, there's a very real risk that people won't realize that, if you are an adult, you will be required to upload a photo of your state ID. Prople might support the bill and only realize what it means in practical terms once it is too late and it has become law.
It isn't clear to me if requiring photo ID is a practical requirement or a decision the two incumbent vendors have made for their own reasons. My guess is that it is the cheapest and easiest solution.