Don’t bother trying to communicate “how it works”. Smooth brains won’t retain technical details like that, and you’ll just annoy them if you keep bringing it up.
Pretend to be “the bad guy” and come up with ways to abuse the data… abuses that family members can relate to.
Location data reveals patterns of movement, like when you are or aren’t at home. This can easily be used to work out routines (like work, school, or shopping) where you won’t be at home. Perfect time to burgle the house. Location data can reveal when a child is walking home alone from school, or waiting at a bus stop. “Hello cutie. Want a lollipop?”
Location data reveals shopping behaviour. If you frequent expensive stores, someone can easily deduce that you have lots of disposable income, and that your home probably contains valuables worth stealing. If you visit “K9 Munchies” or “Wet Noses Vets” on a regular basis, they know you own a dog — but if you don’t visit a vet on at least an annual basis, they know you don’t have a dog and that breaking into your house would be that much easier.
Location data reveals assets. If you visit “Northside BMW” every six months for servicing, they know you drive a Beamer/Bimmer/Beemer. Worth stealing from your driveway, or from the carpark when/where you go shopping? If you stop at charging stations on a regular basis they know you own a Tesla or some other EV. They might then steal it, key it, spray “Elon Sucks” on it, or set it on fire and then pull away rolling coal.
Location data exposes the social network. If you visit friends on a regular basis, then their names, addresses and even phone numbers can be ascertained (by doing something as simple as stealing mail). It’s then trivial for someone to socially engineer you into doing almost anything. Imagine getting a call from an unknown number, but when you pick up the person on the other end says “This is Steve. I’m an EMT. Your friend Josie has been involved in an accident at the corner of 3rd and 6th. She’s asking for you. Can you come and be with her as we go to the hospital?” Or a text from an unknown number: “Hi. This is Sarah. I just got carjacked! They got my handbag, purse, phone, everything. Am sending this from the phone of a witness. Can you come pick me up? Corner of 3rd and 6th.” You’re not just exposing yourself to abuse, you are exposing your friends as well. Are they OK with that? Have you even bothered to ask?
Location data exposes medical conditions. Does the world need to know that you went to an abortion clinic, or visited a sexually transmitted diseases clinic three times in June, or made multiple trips to a specialist that only installs lapbands or performs liposuction for overweight/vain people?
Location data can impact insurance. Will your insurance company deny your medical claim on the basis of “pre-existing condition” because of visits to medical facilities in the months before the claim, or refuse to cover repairs costs following a car crash because your average speed just prior seemed to be slightly above the legal limit, or because you visited a bar?
Location data exposes sexual preferences. Why are you visiting a gay bar every third weekend? Why are you shopping at “Big Black Dildos ‘r’ Us” every-now-and-then?
Location data exposes infidelity. Why do you regularly visit a male friend 15 minutes after your husband leaves for work?
Location data can implicate you in crimes you had nothing to do with, and didn’t even know had occurred — like this and this. You can lose your job, your reputation, your friends, drown in legal fees, and none of that magically repairs itself even if you ‘win’ in court. The damage is done the moment the accusation is made.
And so-on and so-forth. If you know your aunt (or whoever) has insecurities of a certain kind, exploit them. Make it personal. Use examples that resonate. Don’t try to be time-efficient and bring this up around the dinner table with lots of people present. For it to be personal you need to be talking to them 1-on-1. Don’t overload them with lots of examples in a single conversation. Drip-feed the examples to them over time.
BUT… leave out the fine details. The human imagination will fill in the blanks with more terrifying/horrible/sad/embarrassing details than you can ever think of. Let their own imaginations do the heavy lifting. Draw the skeleton then let their imagination flesh it out. Let them convince themselves that this is something they want to avoid happening to them. Then it’s their idea; their decision.
Rest assured that no matter what immoral, unethical, depraved, sick or perverted examples of abuse you can come up with, there are millions of people out there that can come up with things an order of magnitude worse.
For someone to want to avoid doing a certain thing, they need intrinsic motivation. Relatable examples of the abuse of location data can provide such intrinsic motivation.
PS: Keep an eye out for news reports of such abuse. Your family may think the risks are all just in your over-active imagination. When Channel 7 or The Herald reports the same thing you’ve been warning them about, however, it becomes real. You’re no longer a paranoid kook — you’re a prescient guardian.