Speed camera flash

No they don't. If you don't see a flash you can still be done.

And can you be done for multiple times on the same motorway Ina span of 30 minutes? Given it actually occurred unknowingly and since one didn't notice a flash she didn't know tgere were speed cameras?

Not sure what you mean by unknowingly. You don't need a flash to tell you you're going over the speed limit, all you have to do is look at the speedometer. And, yes they can get you multiple times on one roadway in one span of time. Anywhere in Europe you have to watch your speed because they don't give you the leeway that you may be used to in the US (10 mph over the limit is common here without being stopped). It's the driver's responsibility to know how fast you're going and what the limits are where you are driving.

Robert,

can you please share the circumstances of what happened to her and how many tickets you have received? And from whom?

Hope she had the vignette for driving in Switzerland. If not, there could be serious Swiss Franc (CHF) fines in her future.

The driver could have easily passed through several speed cameras. With modern digital camera technology, a flash is not always needed. What time of day did the infractions occur?

I don't know if Switzerland is using something like the Traffic Tutor system developed in Italy, but it's possible. That system registers both instantaneous speed and average between two points, using automatic license plate recognition. Exceed the limit in both parameters and you'll get two tickets.