Why are license plates for bicycles no longer used? Bicycle license plates were quite common in many countries before, during, and, depending on the region, also after WWII. In Poland, for instance, it was obligatory until the late 60s. I've found that in Switzerland some kind of license plates (Velovignette) were still in use until 2011. 

I'm curious why countries retired such regulations, and what are the pros and cons of that situation. I'd like also ask if there are still some countries that require cyclists to register their bikes with some authority and/or are obliged to have insurance etc.

Example license plate below:
In the Netherlands at least:

The license plates for bikes were tied to the taxation of bikes. You needed to get a new plate every year.
The taxation lasted until WWII. The Germans abandoned the tax.

After the war the tax wasn't introduced again so the plates were no longer needed.

It was speculated that after the war the taxing of cars more then made up for the not taxing of bicycles.