//Do we get stories of say Americans who can't fly to say Germany or Spain as there passport is 10years old...//
Probably not because it's not the sort of thing that would interest readers of UK newspapers and even if it did, it could not be blamed on Brexit, so not worth reporting. As well as that, I imagine the one in three US citizens who do hold a passport check the entry requirements of the country they plan to visit. This is what normal people in normal countries do. They don't fail to check, pitch up at the airport and then bleat to the press that they have been denied travel.