Taler isn’t a general payment solution, it’s designed so that separate entities can have their own way to handle small transactions. For example, you attend a conference and deposit some cash into the event, and then you go and use those tokens to exhange for various stuff at the event, and the event organizers settle up with merchants after the event.

Rolling this out on a more global scale mea a you’d need some major institution, like a bank, to back the currency and handle settling up. AFAIK, this hasn’t happened anywhere and isn’t likely to happen because banks already have a system that works that requires far less effort: credit and debit cards.

We already have a solution here that has some market presence, and it’s cryptocurrency. Get some Monero and you can go buy stuff today without those transactions being public. The fees are minimal, transactions are fast, and merchants exist. The main issue is the negative public perception of cryptocurrencies, which is mostly due to speculation and bad actors running scams, but there are solid, proven currencies that can be useful as a cash alternative.