I am assuming that the sub groups were not allowed to split up in the task.

The scene with the four guys standing outside the shop waiting for it open after the lunch and the obvious thing was for two of them to go away and find some other item. They did make them look a bit like idiots when in reality they no choice but to stand around doing nothing

I guess this is for filming reasons but they should really have made it clear to viewers

There are lots of 'hidden rules' in the programme, the buying & selling tasks especially. It was several series in before the 'no internet' rule became apparent. Also the 'you must get a discount' rule wasn't made clear for a while either.

Yes you are right - there are only two film crews per team so they can't further subdivide.