Charles Ellson wrote:

The trouble with that is that it opens the door to defendants claiming
that it [using a telephone] was not unsafe in their individual case
and requires case law of the necessary nature to disprove every such
claim. The current law now addresses a specific improper action with
common undesirable consequences and takes away the argument

The problem with banning one specific behavior is that it's an unsustainable
approach to treating the sypmtom, not the problem. By your logic, we should have
- driving while eating
- driving while applying makeup
- driving while talking to a child in the back seat
- and on and on and on...

Even assuming that all possible bad behaviors could be defined (a logical
impossibility), the delays in getting laws to prohibit each such behavior would
put you in a permanent catchup mode.