Rhino,
Perhaps within Germany and/or the Schengen area some airlines may be a little laid back on ID check. But not elsewhere. In the UK, for example, one is required to have some form of picture ID on all flights, domestic or International.
The airlines do care about ticket transferability. Security is one aspect but tariff integrity and maintaining control on their sales are others. (I'm not defending their reasons)
Some of the LCCs may permit transferability, provided it is done through a ticket reissue (e-ticket included), but many of the network airlines do not.
For example AirBerlin:
3.3.1 The Airline or an Operating Air Carrier will only transport the Passenger upon presentation of a Ticket made out to the name of the Passenger.
6.3.2 The Airline or the Operating Air Carrier will only transport a Passenger upon presentation of complete and valid travel documents and a valid passport/identity card/visa or, in the event of loss …
Lufthansa:
3.1.1. We will provide carriage only to the Passenger named on the Ticket and only on presentation of a valid Ticket …
3.1.2. A Ticket is not transferable.
3.1.6. ... you shall not be entitled to be carried on a flight unless you present a valid Ticket issued on your name
Right to refuse carriage
7.1. In the reasonable exercise of our discretion, we may refuse to carry you on your journey or onward journey… if ...
7.1.8. ... you cannot prove that you are the person named in the ticket,
In the case of Lufthansa these provisions have been tested in the courts.