I'm managing without UPI on my trips to India but I must say it's getting increasingly annoying not to be able to use it. Cash works fine at the very low end stores for minor purchases, and credit cards work fine at the upper end for hotels (esp. those catering to foreign visitors) and good restaurants, etc. It's the "in between" zone that's becoming increasingly difficult to navigate with shopkeepers who are reluctant to accept credit cards (especially foreign cards) because of the processing fees they have to pay, and where the amounts are a bit more than can be handled without carrying loads of cash around. It's awkward, to say the least, to have to resort to doing bank transfers, painful to ask for bank account numbers, etc. while everyone around you scratches their head and says, oh, why don't you just use UPI...