Route the pipework inside, or use pipework which is strong enough to resist vandalism and not worth nicking, such as iorn, attached strongly enough to prevent yanking off, or route copper outside only where it's well out of reach or the location physically secured against public access.
Maybe use of auto-shutoff valves where pipework is located outside. (They're commonly used in France, but I think they require increasing the gas pressure by 1-2 mBar.)