It costs too much to monitor for that and send bills, that the actual cost would be darned expensive.

Possibly cheaper in the long run would be to levy a parking tax into your general municipal taxes (and/or pump taxes, if your city has jurisdiction to). A lot of smaller towns have done this, and done away with meters and parking enforcement officers.

The problem I see with this is that parking meters are in place to regulate how long people park. In areas with stores the meters have time limits which are supposed to be set so that there is plenty of parking for shoppers. You are technically not supposed to keep feeding the meter and actually move your car. So municipalities probably wouldn't want to institute a payment policy that would encourage people parking and leaving their car for days.

In the town I live in they have removed most of the parking meters at the request of the merchants. The shop owners were buying parking tokens from the city to pass out to their customers anyway. Now they simply pay a fee to the city. The city erected two hour parking signs to encourage people to move their cars.

Problem is, they don't. They only move them far enough to erase the marks on the tires that the parking monitors dab on, about three feet. Mostly it's the people working in the area who do this, thereby effectively removing a parking space for potential shoppers. And everyone wonders why the downtown area is dying...

A consultant recommended years ago to reinstall the meters and charge a penny per hour with a two hour limit. That way parking would still be cheap and workers would have to spend more time than it's worth finding a new place to park every two hours. (They would pay the per month fee at one of the lots instead...)

So far this idea hasn't gained any ground and downtown is still dying.