Well, EU doesn't have federal government or something like the
FHWA in the States to take care of the highways as well as the fact that the countries in the EU vary in GDP/capita from as high as 105.000$ (Luxembourg) to as low as 6.200$(Bulgaria) so relatively, not all countries governments can afford the same expenditures. The best designed highway system I would believe is the Autobahn in Germany but I remember reading somewhere that Spain spends more than any EU country on their roads (or at least they did until the crisis hit).
Here in Cyprus, highways are ok but city roads leave a lot be desired...