Amazon's Price Check app lets customers use a smartphone to scan the barcodes of items they find in a retail store. The app does the comparison shopping, and tells them if a better deal on the same purchase can be had online. This is driving brick-and-mortar merchants bananas.

The online retail giant already enjoys a major tax advantage: in most jurisdictions, Amazon collects no sales tax on customer purchases. Now they're giving people who have already come out to stores a reason to not spend there, presenting another potential threat to small businesses in the height of their busy season. Amazon is even throwing in a 5 percent discount on items that customers scanned in-store before purchasing online.

Resistance is growing, the Los Angeles Times reports.

Sen. Olympia Snowe, (R-Maine) entered the fray, calling the promotion "anti-competitive" and "an attack on Main Street businesses that employ workers in our communities."

...

Snowe urged Amazon to stop the promotion being offered Saturday. "Small businesses are fighting every day to compete with giant retailers, such as Amazon, and incentivizing consumers to spy on local shops is a bridge too far," she said in a statement.

Retail groups agreed. A spokesman for the Alliance for Main Street Fairness said "no retailer can compete" with Amazon because as an online retailer, the company is not required to collect sales taxes in many states.

The Retail Industry Leaders Assn., which represents many big-box retail chains, said the app unfairly encourages shoppers to use bricks-and-mortar shops as "showrooms" to check out a product before buying online.

But Amazon is not backing down, and consumer advocates told the Times that the app was good for shoppers. They're the ones who will enjoy better deals as a result. If anything, it improves the competition that business advocates say capitalism needs to thrive, one advocate told the Times. "It doesn't make sense to call it anti-competitive behavior," he said.