in a practical sense, UPI is primarily positioned to facilitate digital transactions in a cash-first economy. while it would be nice to have safeguards against scams, especially as qr codes become more ubiquitous by the day. however, paying with cash did not have any inherent safety features either, so it is equivalent in terms of risk imho.
although i do have a personal anecdote of getting a payment reversed when a pos double charged me. i did have receipts and had to wait a few weeks, but in theory it is possible in regular scenarios (i.e. when it is between an individual and a business).
So stringent in fact, that RBI shut down PayTM Payments Bank which was most popular market leader in that sector, because PayTM flouted the mandated norms for digital payments and payments banking.
That is also beside the fact that UPI platform has high uptime and rarely faces any outages.