Cell service requires radio connectivity to a cell tower, which depends on distance and local terrain. It's quite common to have connectivity on a ridge or mountaintop, but lose it in a valley. Starlink works as long as you can see the sky.

Also 5g speeds in a suburban or urban area are significantly different from the wilderness. I have some property an hour drive from Portland. While some people can get a signal and their phone says "5G", the distance to the cell towers is great enough that actual connectivity is extremely spotty. It takes minutes to download a single photo. Starlink is much more consistent. You actually get better performance if you're farther from civilization.