2 Things - well maybe 3:
Porter - Tower movements are calculated either from flight progress strips or running sheets and are retained as evidence - I think non-towered airports record calls so they can send out bills.
Pera - The concept of a remote tower controlling multiple airports only works if the country regulations require ATC for IFR PT movements, I think that is the case in Sweden and is the reason why SAAB invented remote towers. Everyone else has jumped on the bandwagon because the bean-counters immediately saw the cost savings. Unfortunately for the bean counters the requirement to have an ATC Tower varies between countries. Australia is an extreme example where we allow PT aircraft to fly instrument approaches outside of controlled airspace into uncontrolled airports - very few "advanced' countries do so because it is too riskly. So why would we need remote towers? My solution, where the aerodrome needs a Tower (Ballina comes to mind), is for the airport to build a reasonably priced structure, staffed by reasonably paid controllers whose job it is to regulate runway movements and ensure that the circuit area remains safe (see Griffo and Porter comments), and instrument approaches are protected during daylight hours. This is the way I think Airservices is heading however my previous remarks about free-enterprise are still relevant. If the controllers (and Firies) work for the airport and are part of the local community then I believe Australia would get more efficient and less bureaucratic airspace management.