Airlines have a very low profit margin business. They earn very less for the amount of money they invest in the product. Therefore, capitalists are not very interested in the dividend. It is also a high risk business as the market is very volatile (see current crisis) and have a high merger/fail rate.

Lufthansa is one of the top carriers in the world with a solid infrastructure and network. The eliminated many competitors by just letting them starve themselves in low prices while Lufthansa never compete. I personally do not doubt their value. But the overall market is not an investment friendly one.