> I have no doubt that some future techno-currency scheme could be made that could serve as currency AND change its value depending on who is holding it.
Then it's not a currency, is it? The whole point of currency is that it's abstract and fungible. It's not abstract or fungible if one person's holding of a currency is worth more than another. A seller can charge a single, fixed amount for some good or service. But if some standardized currency is worth different amounts depending on who holds it, you can no longer exchange a fixed-value good for a fixed amount of the currency: you need to charge more or less depending on how much each person's money is worth. You can't flip this around and say that the seller should just deny selling to people whose currency is worth less, because that implies that you can accept a dollar from one customer and a dollar from another customer and their values are different, which means it's fundamentally _not_ who's holding the currency that matters, which makes the whole scheme moot.
What you're describing is social credit, which is becoming increasingly common outside of the US. It's not that your money is worth less, it's that you're deemed less trustworthy or less valuable as a customer (perhaps you write in to customer support too much, or you have returned too many items). If a business knows this, they can compensate by requesting a different amount of money. But that's not something that's affected by whether the currency is cash or digital or anything else; the adjustment of price happens before any exchange of value.