During my US trips, I visit a lot of electronics stores, particularly Fry's Electronics in the US western states and the usual shopping mall national brand stores. I can't say I see a lot of people tapping away on their phones to look up prices. As others have said, impulse buying still happens.
Today, my wife is going to an electronics store to buy two cameras for her work. We did the research by saving the junk mail for a few days and comparing prices on the dining table and then going online to check specifics such as the battery type. :)
I am known to have done research on a specific model of monitor, found the best store, yet walk out with something else that was new and attractive. And, sadly, I went home and checked this model, only to find I could have got a better price elsewhere. :)
I do see a few supermarket shoppers in Australia walking around with a competitor pamphlet as if to compare prices. The smart phone isn't useful because our supermarkets have prices set by the store manager. Many of our malls have the two major chains in the same complex and it is possible to take a trolley load to your car and go back to the next supermarket.