>The answer is to have some mechanism whereby people who run into these issues can pay (once) the small cost of being validated in an alternative way (like, actually talking to a human and explaining what's going on, which is how these issues got solved in meatspace originally)
The answer is to have electronic money accounts and transfer services be operated by the government, and to make it the government's problem to go after criminals rather than have the businesses left holding the bag.
That way the business is not incentivized to discriminate, as long as they get the money through the government money transfer service, they are guaranteed it as if they received cash.
Corollary is that you also need a law that guarantees the right for everyone to have an electronic money account that can send and receive money and that no government can take that ability away from you at any point in time.
And the government has to operate an identity verification API. And again, the onus is on the government to go after criminals committing fraud.
Once you put the onus of fraud or damages on a business, then every business will obviously start discriminating to minimize those costs.