All customers get confused by that pre-authorisation thing, it was explained to everyone very well by email when it was introduced about a year or so ago, unfortunately it was well hidden in a very long FN email about E-scooters in Italy, and all other stuff. Hence nobody at all ever read all of that email (except me).
The simple thing fer drivers is just to assure the passenger that they will only be charged the metered fare.
And just input the proper metered fare and that's it.