Roku’s humble $30 streaming TV device is mediocre at best. It stutters and lags while moving through menus and apps, its single-band wireless connection is a generation old, and its remote control uses clunky infrared technology that requires a clear line of sight to the box. Given that Roku’s Streaming Stick eliminates all those problems for just $20 more, it’s hard to imagine many people buying the Express instead.

Yet Roku is having no trouble selling its cheapest streaming device. In its recent IPO filing, Roku said the Express drove a 37% year-over-year increase in device sales during the first half of this year. Devices under $50 now make up more than two-thirds of Roku’s U.S. sales, and the company’s average selling price is down to $47 in the United States, according to the NPD Group.

At $150, the current Apple TV costs more than three times what people pay for a Roku player on average. But while Apple’s streaming box is miles ahead of the Roku Express in performance and polish, the experience isn’t much different once video starts rolling in an app like Netflix. That may explain why Apple TV is bleeding market share to Amazon and Roku. People just don’t have much incentive to pay a premium for a streaming box.

Next week, Apple is rumored to announce a 4K HDR Apple TV, which should at least help the company reach feature parity with its competitors’ streaming boxes. But don’t expect the new format alone to drive a turnaround in market share. For Roku, the $75-and-up price categories that includes its Premiere+ and Ultra 4K HDR players only makes up 22% of sales, according to NPD. And while Amazon has offered a 4K Fire TV box since 2015, the cheaper stick has only gained share since then.

The notion that Apple must respond to low-cost competitors with its own cheap products is one of the most banal arguments in tech punditry, and Apple is usually wise to ignore it. But the business model that has worked so well for the iPhone, iPad, and Mac–differentiated software enabled by premium hardware–doesn’t translate to the streaming TV business, where content is king. Without either drastically lower prices or a breakthrough advantage in content, the Apple TV will continue to struggle.