Speed pay Metro (Inventors of Token numbers)

I can't understand what's the purpose of this 3rd party as all water must feed from the municipality anyway. Municipality also has prepaid water meters that works effectively. Metro charges virtually almost double for per k/L. The estate I stay in did not give us a choice so we were forced to use this 3rd party being metro however all I no is I paid for the meter cash through my HOA. What exactly is this Metro providing me with a token number and water that comes from the municipality.