It says a lot about the current state of the European Union that an influx of ~1-1.5 million refugees, by all accounts a rather tiny proportion of the European population, has created a traumatic political crisis that's devouring the system. The United States managed to handle the Vietnamese and the Cuban refugees wave, which were on a somewhat similar scale relative to the proportion of the population, with relative ease in the past. Similarly, refugee crises in the past were handled admirably by Europe, of interest to this thread ought to be Greece's response to the influx of Albanian migrants in the 90s, the response to Somali refugees etc.
First of all both the Vietnamese and Cubans arrived in smaller number over a longer periode than the amount of refugees Germany alone received in 2015. Sweden have received more refugee than USA did in the Mariel boatlift, and it's a country with 1/30 of the American population. It's why we see the significant political crisis in those two countries over this, and moreso in Sweden than Germany.
Also right now USA take in 70 000 refugees annual. Which is why the American moral high ground on this point is built on hot air. In fact the numbers of Cuban and Vietnamese refugees USA have taken in are 300 000 and 800 000. As comparison Denmark received 7500 refugees in 2013 and 14700 in 2014 of which around half get asylum (3900 and 6100). Denmark have 1/60 the population of USA. When you make than calculation, it means that as percent of the population Denmark took around 25% more refugees (compared to populatio size) in one year (before the refugee crisis) than USA have taken in Cubans over 50 years or 45% of the amount of Vietnamese USA have taken in.Plus, doesn't Germany have a moderate number of Vietnamese, many who came over in refugee-like situations. Of course, many of them were apparently deported because the poitical powers that be have no interest in aiding non-Muslims, but the ones that were able to stay seemed to have integrated into German society very well. It's almost as if the problem was with Muslim migrants, not German/Danish/Swedish/etc. society.