Ist there really a significant number of immigrants which choose Switzerland as a transit country? If you try to get from e.g. Italy to Germany, why would I voluntarily leave and enter the Schengen area if I could go via France or Austria instead?
Switzerland
All things Switzerland!
Switzerland is in the Schengen area.
Oh, you're right. Nevertheless, there is a far stricter border control between Germany and Switzerland compared to Germany and France. I drove to/from Switzerland maybe 20 times and most of the time there are people looking at the cars. I got pulled over twice. I drove to/from France way more often and I never even saw the border patrol. So if I planned to immigrate illegaly I'd definitely prefer France over Switzerland.
Are they checking your passports during this stop? Or just doing customs checks?
Both. Once I was stopped with the car and 3 other people. We all had to show our passports and they inspected the bags and trunk etc. The other time I sat in a travel bus from Munich to Milano and when crossing the border, they've checked everyone's passports, had a look in the overhead compartments + the baggage storage area in the bus but without deeper inspection of specific luggage.