For the same reason Fred Smith and the whiners at UPS first complained , then lobbied the US Congress to prevent DP-DHL from having a competitive and level playing field in the USA. You people think that America has the right to do whatever is in its interest economically and sod the rules , screw everyone else. Your time as an economic bully and powerhouse is quickly coming to an end.
The Chinese have allowed FedEx and UPS domestic rights in China , ( something like 8 cities and 6 cities respectively) If it is good enough for you in China , why not a foreign integrator in the good ` ol USA ? Your answer is always... well that`s the rules. You have been bending the rules for way too long. And we haven`t even begun to talk about taxes.....
Don`t throw FedEx and UPS out of Europe , just insist they operate European registered aircraft with EASA licensed crews with the right of abode. THAT IS FAIR.