You're not thick but its not correct to say there are no surprises (problems) when it comes to the road rules.
First there is a common understanding that passing (in the same lane particularly where there are medians) is the same as overtaking which is defined as such.
In discussing overtaking there seems to be too much emphasis on marked lanes and very little on 'line of traffic' which are very different.
(c) passing the other driver while travelling in the adjacent marked lane or line of traffic
When a car or truck passes a cyclist it does not necessarily have to change lanes because of the line of traffic requirement. Wide kerbside lanes are specifically provided to be wide enough for cyclists to be overtaken within the same lane. In this case the line of traffic refers to the cyclists line which is very narrow - having a distance between the two lines of traffic, such as 1.5m is a massive improvement.
Think of a cyclist as defining his line of traffic, effectively this is a space just 1.0m wide. These are easy to see as they exist as a 'marked lane' and are called Bike Lanes. Probably their main benefit (apart from conning inexperienced cyclists that they are safer) is for the motorist as they remove cyclists from the main traffic lane and keep them away from the cleaner safer part of the road.
I see many horrendous videos of cyclists being passed which are clearly less than half a metre clear so, with a 1.5m rule evidence of a breach would be easy to show. Ask Aushiker what the WA police say when he shows them a near pass "no offence observed" and think whether that casual rejection would still be appropriate where the test would be 1.5m.
Rules are there to educate, modify behaviour and only as a last resort enforce. Why would anyone not support such a sensible rule that provides as much room to a smaller cyclist as a motor vehicle always provides to another bigger vehicle.
Put simply fear of being hit when passing too close makes motorists take greater care - with big vehicles. When the fear of passing too close is only felt by the cyclist being passed there needs to be a law that provides an additional fear for the motorist to keep clear.