That is true for many cell plans. But if you use an app to do the tethering (like I do), to the carrier it looks like generic traffic. They don't realize its tethering. My plan is unlimited everything (call, text, data), but slow. The data bandwidth is capped at 3 or 5 mbps. That would be annoying for web browsing on a PC, but its fast enough for watching a camera live feed. Since its unlimited, I could watch the feed 24/7 if I wanted.
This was the cheap and easy option to test out my plans for using generic sercurity cameras as trail cameras. When we get a tiny house out there, we'll get starlink and instantly have fast wifi all over the property. But until we've got a place for the starlink, the cell phone is working well surprisingly well.
That's why I brought it up. If a person wants low cost wifi in the middle of no where, that's just fast enough to browsing live video feeds, it can be done cheaply.