100MB is enough to send hundreds of free internet messages such as iMessage or more traditional chat apps which avoids using limited text messages on the plan. That’s a legitimate reason to keep it enabled.
If you don’t use text/call data and can get away with mostly messaging on wifi and then having that the cell connectivity for wife check ins or emergencies at work, this plan costs like $5 a month or something. Compared to a jump to $20 or higher at the next tier. For a lot of people, that’s significant.
Work arounds shouldn’t be a real solution anyway. People can’t restart their computer to solve basic IT problems. Imagine if they had to change their phone settings through multiple layers of menus.
Aside from all or nothing cell data toggle, I’m not even 100% sure if disabling Find My’s data connection stops this situation. It could go through an unknown system service for all I know. Anyhow, I classify this as an essential security app that would be unfairly unreasonable to have to opt out of for this specific use case.
Your paid phone and service just shouldn’t be freely used without your consent to benefit other people while costing you money.
Maybe it’s a nice idea, but that’s not how anything works in the society we currently have.
Edit: also another thought on this topic as a whole… if you’re the only person who goes through a specific area that someone set up with AirTags, wouldn’t that make you personally identifiable when the AirTag owner gets alerted?
You could set these up in a vault for example. Imagine the WiFi signal gets through when it’s open. When the one vault manager comes to complete the alert circuit, you would have the times he’s there or even as a boss you could see if he’s skipping his duty.