Actaully Dr Smith I disagree..

You can stop and talk to them.  Now weather they talk to you or not, is another story.

You, me, WE have every right to stop and ask.  Remember they work for US, paid for by tax payer money. 

So I would say yes, stop and ask.

Be polite, be nice.  They may not open a window for you they may just shout through the window.

But you have every right.

To answer your question, I believe during the day, No, no flash needs to go off.  They don't use it.  Even if they put it out.  I was told by one of them, they actaully put the flash out, to give motorist a better fighting chance that they are around. 

OK he's doing a sh*tty job, doens't agree with it, but in his own way he tries to warn people.  Putting the flash unit out during the day, is his way of helping. 

At night, unless I'm mistaken, they still are not using flashless camera's yet..