> Explain to me then how an Apple TV device for $125 (Retail! not BOM!) can be staggeringly faster and generally better than any TV controller board I've seen?

This is the result of Apple being vertically integrated and reusing components from other product lines in products like Apple TV. The SoC used in the Apple TV are from lower-tier bins of chips produced for mobile applications.

With the Apple TV, you are getting a SoC that is effectively the same as a recent-year iPhone. With most other Smart TV devices you are getting a low computational power SoC, Raspberry Pi tier, with processing blocks that are optimized for the video playback and visual processing use cases.

Apple also does this with the iPhone where the non-flagship variants will reuse components or designs from prior years.

Television/Smart TV manufacturer margins are in the single-digit percentages and the Samsung and LG tv businesses are significantly threatened since their high-volume products have been commoditized from Chinese producer competition. Most potential customers are shopping based on screen size per dollar, versus specs like peak luminance and contrast ratios. Flagship TV products like "The Wall" are low-volume halo products. Lifestyle products like "The Frame" exist because they are able to differentiate to certain segments of customers that place enough value the packaging aesthetics to buy a higher priced product with better margins for the manufacturers.

Most other hardware device manufacturers are jealous of Apple's margins. Nvidia would probably be one of the few exceptions.

Thin margins on commodity tier products drive these manufacturers to cut their BOM costs as much as possible, even if it makes the product worse in other ways. This is also the big driver for why ads are appearing as part of the Smart TV experience at the device/screen level. Vizio for example shared that they made more money from their ACR business than they did from the device sales themselves. There are companies with business models based around giving you the screen for "free" in exchange for permanent ad-space. Even adjacent products and companies like Roku have business models where they are selling their hardware at near break-even cost points because their business model is built around 'services' from having a large user audience.