This law is unnecessary because it is already an offence to drive carelessly or without due care and attention. The law becomes ridiculous when it is tautological.
If the existing law was rigorously and fairly applied then there would be no need for a ban on mobile handsets and no need to debate the use of hands-free systems. If the driver is dangerous or careless then he/she is committing an offence. If no danger was caused then there is no reason to prosecute anyone.