All governments spy on all others to the best of their ability. If Germany isn't spying on the US that only means their intelligence service is not competent. Of course more effort is and should be spent on potential enemies, but there is too much in play to not spy on your friends if you can get by with it.

Note that success of spies is not guaranteed. It is possible Germany doesn't have spies in the US because despite trying they haven't found any.