You do if it's an RPT operation. The 20,000 kg waiver only applies to charter operations.
From the regulations;
4.02 Meaning of
screened air service
(1) An aircraft must be a cleared aircraft before departure if it is operating a regular public transport operation or an open charter operation with a maximum weight of at least 20 000 kg.
Aviation Transport Security Regulations 2005
Most business types have no checked baggage & that's where the $$$ are.
In my experience they like to have the option available, even if they don't always use it.