Apple IDs have moved on from being a sharable resource. With the release of the various Continuity features, an Apple ID (when used for iCloud) is now, more than ever, like a phone number. Not designed to be or easily shared.
Instant Hotspot in particular is a convenience for a user who has multiple devices. Not for a family or group of individuals.
You've been informed by Apple of the risks.
It allows other people, whom you generally trust, to abuse your LTE data plan while you are under the clear understanding that you have explicitly prevented them from doing so.
This statement puzzles me. How can you sort of trust someone?
And then, after they abuse that trust, (your words, not mine) continue to trust them? Fool me once, shame on you...
And you have not at all explicitly prevented them from doing so. If you change your Apple ID password and force them to get their own, your LTE data plan sharing issue solves itself. That's explicitly preventing them. Asking them nicely doesn't appear to be working for you.
You have Family Sharing available to allow the sharing of most iTunes purchases. You can even refuse to play that game by sharing an Apple ID for only iTunes purposes, but not iCloud. This also solves your Continuity issues.
Multiple solutions.
No fingers in my ears. No head in the sand.
End of story.
