Comment by iridium184

Air traffic is not taxed heavily compared to other modes of transport - on the contrary, it is very heavily subsidized (at least in Europe): Regional airports often strongly depend on state subsidies, airlines are exempt from petroleum taxes, flight tickets are VAT-exempt.

In Germany (and also e.g. Switzerland), long-distance trains are expected to run either at cost (or make a profit). Short-distance trains (regional transport) are usually subsidized.