Your flights in Europe must not be as full as ours in the US. I carry two flightdeck jumpseaters on many of my flights, some of them 5 hours or more. Every flight in the US is packed, particularly in the summer. Many of us also commute during the year so the flight deck ride is our ride to work.
With airline consolidation and the trimming of capacity there are less seats for more demand. Great for the company, not so great for one of the few benefits that airline employees have. All our aircraft come with 2 FD jumpseats. I know that I the past other airlines have taken delivery with just one but I doubt that any US carrier will do that again in the future. They like it when we make it in to work.