I think that happens a lot with smaller purchases, like a pair of cheap headphones or something like that. With larger dollar purchases, after you factor in the price difference and taxes (assuming free shipping), the price difference can be significant.
That said, you have some big box stores flourishing, like Costco - why does Costco thrive while Best Buy struggles? I think it's the experience at the store, history with the store, and general approach.
The way I heard it, Costco basically breaks even on the merchandise, and it's the annual membership fee that keeps the lights on. So they're well-situated to be a subscription showroom service for their members, with or without fulfilling many orders on the spot. It probably helps that their staff are treated pretty decently by retailer standards.
That said, you have some big box stores flourishing, like Costco - why does Costco thrive while Best Buy struggles? I think it's the experience at the store, history with the store, and general approach.