Even a modest change reducing a speed limit on a residential street from 50 to 40 undergoes heavy review and is unlikely to happen if even a small vocal minority opposes it.
That doesn’t happen in my city.
For example there are two intersections on my commute that are virtually identical (they’re on the same stretch of highway and they are exits for neighbouring beach suburbs with the same intersection design). One of them is 100km/h for through traffic and the other is 40km/h. Why? No idea. But if there was “heavy review” then surely they would have the same speed limit. It’s been like that for something like ten years, locals just ignore the speed limit on the slower one and if there’s a cop car behind you they’ll be annoyed if you slow down. Police setup speed traps near that intersection all the time (almost every day), but I’ve never heard of them doing it on the intersection. They enforce the 100km/h limit, not the 40km/h limit.
Going back on topic - this is a bridge built specifically for cyclists. The speed limit is absolutely intended to be obeyed by cyclists and has nothing to do with cars. And if you can’t ride 10km/h safely then you shouldn’t be riding at all.
That doesn’t happen in my city.
I won’t speak for what goes on in your city, but it is definitely the case in Brisbane. And honestly, I’d be surprised if the one specific example you’re pointing to isn’t an oddity for some particular reason, and the general trend is the same.
We literally had the Lord Mayor call it “socialist” to suggest that 30 km/h speed limits on local residential streets is best practice. That same Lord Mayor’s government voted down a petition that was apparently signed by every single resident on the street to reduce their speed limit because it was being used for ratrunning by trucks doing construction nearby.
I’m in regional QLD, and this is no where near the biggest problem we have.
For example a major highway (National Route 1, which passes through every major city in Australia) goes through a a mountain range just 20 minutes from the CBD and closes almost once a week for an average of 6.6 hours due to car crashes which are difficult to recover. The detour when the road is closed adds 3 hours to the drive time and worse it’s unsafe (and illegal) to perform a U turn anywhere on the entire stretch of road up the mountain so whenever it closes thousands of people get stuck and just have to wait until the road opens (which again, takes hours). Emergency services are forced to drive on the wrong side of the road around hundreds of narrow blind corners to reach the accident, and anyone who does turn around is risks crashing into them.
A multimillion dollar review into wether something should be done about it was delayed repeatedly for years and then finally carried out during a full covid lockdown when we had the highest number of covid cases the city saw in the entire pandemic and businesses were only allowed to open if they were declared an essential service. Nobody could leave their home except to go to those essential services and even then you weren’t allowed to travel to other cities or towns except for very rare excuses. Traffic on roads between cities/towns, like the range being assessed, was obviously almost zero and surprise! They determined that traffic was minimal, nothing needed to be done, they didn’t observe any crashes during the short review period, and recommended re-assessing the situation in 30 years time. When the population of the city is expected to be more than double what it is right now. Great.
The silly speed limits on my commute are, frankly, way down on the priority list compared to issues like the one I just detailed. I could list more serious problems that are being ignored. And these issues are state or national highways, so the local council doesn’t have the juristiction (or budget) to deal with them.