"But they do; unfortunately they are experts in drafting laws, not experts in what the law in question is actually trying to address."
They are not even that. The work to actually draft the law takes far longer than has been allowed since at least 1997.
What successive governments have done is assumed that the most vocal insider lobbyists are "experts" in the subject. So you get the draft bill's aims prepared by people with a vested interest. They generally either water down any safety regulations - or in the case of "morality" judgements they usually try to make them draconian. The composition of such co-opted "helpers" reflects the minister's prejudices.
When the draft bill is published for public consultation there is then an uphill struggle of damage limitation to get something more sensible into the final act.
The loose drafting then opens up avenues for law enforcement agencies to push the limits - needing defendants' Appeal Court judgements to establish case law protection.