The model may work elsewhere in certain cases to a limited degree (St Gallen had less than 92,000 passengers in 2015, much smaller than SEN), but it is often a bad idea in business when a company acts to a significant degree as its own customer - all sorts of perverse incentives can arise which makes middle management do quite strange things that are in the interests of their little fiefdom but not in the interests of the company as a whole.
It also makes other entirely separate companies start to wonder whether things are really being done at arm's length or whether there are some opaque dealings going on somewhere.