It's possible that some 4K movies appear to have the same visual quality as 1080p films due to a few reasons. One reason is that the source material for the movie may not have been filmed or mastered in true 4K resolution. For example, a movie that was originally shot on film and then scanned at 2K resolution will not have the same level of detail as a movie that was shot and mastered in 4K. Additionally, the bitrate of the movie can also affect its visual quality. A 4K movie with a low bitrate may not look as sharp as a 1080p movie with a higher bitrate, due to the amount of data used to represent each frame.
Another factor that can affect the visual quality of a 4K movie is the upscaling process that is used to display it on a 4K TV. Upscaling is the process of increasing the resolution of a lower-resolution video to match the native resolution of a 4K display. However, this process can sometimes result in a loss of detail and sharpness, as the TV is essentially guessing what the higher-resolution image should look like. Additionally, the quality of the upscaling can vary depending on the specific TV and its upscaling algorithms. Some TVs may do a better job of preserving the detail and sharpness of the original image than others.
It's also worth noting that the visual quality of a movie can be affected by the specific display on which it is being viewed. For example, a 4K movie may look sharper and more detailed on a high-quality OLED TV than it would on a less expensive LCD TV. Additionally, the viewing conditions, such as the lighting in the room and the distance between the viewer and the TV, can also affect the perceived visual quality of a movie. So, it's possible that some people may perceive a 4K movie as looking no better than a 1080p movie due to the specific display and viewing conditions they are using.