Natural gas measurement is temperature-compensated, at least here in central europe. You pay for the heat energy contained in the gas, not for the net volume. The compensated heat energy is calculated based on consumption profile of the consumer class (cooking only, cooking and heating, business etc) and temperature profile of the location (pretty fine grained temperature regions).
But yes, you can still trick the meter by cooling the input medium.
One thing that threw me off in Europe is that apartments will still have individually metered water and natural gas (probably paying more in monthly account fees than usage...).
Like a cold water tap, I guess the temperature of the gas can really warm up in the pipes when it isn't run enough to get 'fresh' cold water/gas from underground quickly.
At where I live, trading water is forbidden. We rent appartments and we must not have any profit on the water. Usually, the consumption is separated per person, but sometimes that is not possible (when there are stores, for instance).
For an odd reason, however, flat rate is acceptable, so you can charge tenants a fixed monthly fee and make an actual profit out of it. Sure, there's a risk you set the flat rate price wrong.
But yes, you can still trick the meter by cooling the input medium.