You really think that it turns off the light when you close the door? Your car doors really lock themselves when you step out? Your laptop stays off/sleeps when you lower the lid?
Think again. You may put a camera inside your fridge to see if the light really goes out. If the fridge is smart, it will know there is an observer inside and turn the light off immediately. Your attempt, failed! Next time, try measuring the power consumption with open and closed door. Your fridge is really smart, it will detect the small voltage drop across the ammeter component and will turn the light off the instant door closes. Spoiled measurements. Ha Ha Ha!
Do you recheck your car doors when stepping outside? They may only lock themselves when you check them and not otherwise. How many times we just take it granted that the car is safe.
To cap it all, your wife will only not cheat on you when you are around to watch. Isn’t that correct? You children will not date if they know you are near by.
Ever had the weird sensation of laptop battery dying out very quickly, even with the lid off? Only if you thought to catch the culprit next time, it won’t happen when you are on the watch. Your laptop is no fool and knows you are vigilant.
How would you measure the distance between two locations? Of course, with a ruler. But what really guarantees that the scale is exactly that much long that it says. You may use some other device, but who says that device is accurate in the first place.
This is not like Schrodinger’s cat at all. States collapse into one observable outcome when the box is opened. The cat is either dead or alive and does not go back to uncertain state when the box is again closed. Here, we want to measure the states without measuring.
In essence, it is not possible to verify a system from within that system. Some external component must be involved. But as soon as that component is involved, system boundary expands to include that component into the system.