Technically, the vignettes are required only for Autobahn travel in CH, and toll road travel in A, respectively. Yet, with no vignette in the windshield, and refual to buy one, the control officer would have to decide whether the driver may be sufficiently adept at navigating exclusively off Autobahn and toll road. Also, the cash penalty for violation is indeed stiff, in both countries. Because penalties are due on the spot, one should carry sufficient cash. This is so also when paying autostrada toll or automobile service in northern Italy.
Some countries require a fire extinguisher.
In the event of car theft, when the registration paper was left in the unattended car for hours, your insurance might not indemnify when negligence is potential root cause of the authorities' inability to locate or reclaim the property. Drivers generally seem to take heed, in view of fairly open borders. Valuables left in the unattended car may not be covered by your theft insurance. The courts have ruled driver's gross negligence in the case of keys stolen from the glove box in a locked car. Constant alertness while driving on European roadways.