Non of the Swiss traffic laws and regulations forbids a Swiss resident to drive a foreign registered car. Here all of them, no word, zilch, nada: http://www.admin.ch/opc/de/classifie...lation/74.html
But what may or could be the case is that using a foreign transport vehicle may be a tax and/or duty offense if one does not respect all regulations and follow the requested procedures. Here the custom laws http://www.admin.ch/opc/de/classifie...ion/63.html#63 and tax laws http://www.admin.ch/opc/de/classifie...ion/64.html#64
For ex. it is perfectly legal to drive a foreign car as a chauffeur on behalf and instruction of its foreign user if the foreign user is present.
And as you may see from the SVG and VVV the foreign third party liability insurance or the Nationale Garantiefonds has to pay for damages.
Lawful import (in the legal sense, which is not the same as having something cross the border), which is a prerequisite for registration, requires payment of all taxes and duties, otherwise you won't get a grey card and can't register the car. Thus an import duty offense or not paying all taxes will invalidate registration and nullify insurance coverage.
Driving any given motor vehicle is not a right, it requires permission and fulfillment of certain conditions. It's futile to forbid something (or expect prohibiting thereof) that isn't a right in the first place.
CH law says for CH residents to drive a motor vehicle on CH roads the driver must have a valid license (for the vehicle type) and the vehicle must be registered. This follows directly from it being swiss law, which of course means it applies to CH soil. (Partially) excempting foreigners and/or vehicles registered abroad doesn't invalidate or override that rule - in fact, it's simply outside of its scope.
The particular situation you describe is one of a few rare exceptions (see admin.ch link). The exception never invalidates the rule, quite the contrary.
Kantonspolizei St. Gallen: Nope, forbidden
Bern (federal level): Nope, forbidden
On the parking bit... I always stop at the french side. I took the trouble of reading the rules once (sorry, I can't find it to post a link anymore), and the Swiss side explains that their price difference is reflected on the income power of each country, hence the price difference. Still... I park on the other side. I pay enough already on all the other differences and extra charges for being in CH!
I sometimes take somes flights to get back to my parent's place in France, will watch out prices from now...
Is there a difference in Easyjet prices as well?
Are the white parking zones near the casino still a viable option? Would anybody be so kind and PM me a google maps link pin-pointing the location?