See? It's all discretionary. As should speed limits be (at the discretion of the driver, based on the current road conditions).
The problems you mention have other, better, actual solutions (e.g. cycling lanes, speed bumps before road crossings, ...).
Doesn't the cyclist get a say? Or the pedestrian? Why should just the driver get to decide how much risk to impose on everyone else?
Its not uncommon for cheap inadequate safety measures to supplant real ones.
It's hardly better on rural streets with 100km/h limit and lots of space to overtake. It's not a speed limit issue, it's an issue with car drivers not giving a damn about cyclists and pedestrians because they have no concept of how dangerous this is. Speed limits are essential in a city, and bumps are needed in addition to them.
I have a huge problem with enormous super-highways having 60mph limits or lower.
Some of the roads out where I live were engineered with going 90+ in mind. In fact, there's a tale of an engineer going such speeds and getting out of a ticket by explaining that to the judge out here.
What was the speed limit? When you're over 15 miles from the city, it's 60, but pass a turn in the road and it's 70.
Not all road users are car drivers!