Good points. My point was in response to those asking about driving others, not just oneself. Obviously, one would not double up on fuel cost for every passenger carried. If it is feasible for several to share a car, it makes sense for them to do so.
Fair enough. I was not referring to quid pro quo, but to situations where one person always ends up driving others (which does happen in some circumstances). In that case, being picked up, driven to and from the job and delivered home equates to a taxi service and those being ferried should recognise that and give the driver a drink on top of fuel cost. They can always buy a car of their own or take a taxi if they're not happy to do so.