when is disobeying traffic signs OK?

http://www.treehugger.com/files/2008/07/bikes-and-stop-signs-quote.php

Uptown Waterloo, there is a short street connecting King to Caroline by the mall.
Inexplicably, the parking lot does not have a stop sign. The street does.
There is very little traffic.
Maybe it is for pedestrians?
Actually, they have a crosswalk a mere 50 feet away by the mall.
Uptown just cruising, I move 10-20kph.
Visibility is terrific.
I think there is a bit of a hill there. Keep in mind I use muscle power.
So yup, I use a rolling stop through it.
It may be illegal, but it is not unsafe.

I volunteered for the Waterloo Jazz Festival. I met a young lady who had been struck on the Iron Horse Trail at Victoria. The traffic is killer, and often never lets up.
There is NO CROSSWALK of any sort.
Cars go first. Everybody else can wait.

Near my place, at Westmount and Westcourt Place, there is a traffic light.
The 5 lanes and bad visibility makes jaywalking a risky affair unless one runs.
The walk signal takes so long that I thought it was broken.
This is true of the University UW student one and the Northfield by work one too.

I just imagine the conversation of city planners.
"Well we cannot slow down traffic!"
WHY NOT?

There is a new ?cloverleaf? going in around Bridge Street.
It is already nearly impossible to cross on foot, and is the route to school for school-kids.
It will be worse after.

Themes?
1) too MANY crosswalk options
2) too FEW
3) too SLOW