Alliances benefit all if done correctly, but like an insurance everyone pays in. The Germans literally don't pay in (% spent on defense as part of GDP), deploying troops, partaking in combat operations, number of casualties ( http://en.wikipedia.org/wiki/Coalition_casualties_in_Afghanistan )......... BY ANY MEASURE they do not carry their weight ( https://www.cia.gov/library/publications/the-world-factbook/geos/gm.html ). Alliances don't work when you only pick the battles that interest you and that are low risk with high payoff to oneself but avoid those that are critical to key allies but have little value and high risk to oneself. If everyone did that, you wouldn't have an alliance. What's even worse is when you know others have to deal with the issue anyhow and even though it does benefit you, you hold back because you choose to avoid paying the economic, military, security and political price by becoming involved but still want to reap all the rewards and benefits of this involvement afterward, knowing that other allies are forced to take action.
A historical example where you're most likely able to see it without emotions:
Drugs are killing Germans too. Over 3/4 of all the world cocaine come from Columbia and the cartels are well enough organized and financed to where they hired mercenaries, shot at aircraft with MANPADS (We had helicopters brought down), had armed guards protecting their crops, paid off politicians, murdered cops and judges that went after them (It became so bad that judges would be behind mirrored bullet proof glass and be assigned a security detail with armored vehicles, etc)......... Though the drug deaths and other associated crime was in Germany too as in most Western nations, the Germans chose to sit on the sidelines all through the 80 and 90s during the “war on drugs campaign” which in reality was largely a war on the Colombian cartels and support for the government and security establishment of Columbia. Today Columbia still has issues, but it's better off than what it was 20 years ago, but what did the Germans do to make that happen? Did they have SF there? Did they send people to the School of the America's to train Latin officers? Did they give billions in aide over the years to Columbia to assist the government and its security apparatus in its fight against these cartels that literally have more money than any European defense budget? The legitimate government of Columbia (elected) was waging a civil war with drug cartels that have literally small militia's, their own intel, aviation, snipers, recon communications units (Hell, we kept around Morse code as long as we did largely because of this campaign).
Not only did the Germans not do anything, they exploited this issue in their internal political games. Over and over their media pummeled the School of the America's, portraying it as some despot training center while in reality this training tries to combine the concepts of rule of land warfare and civil leadership over the military as well as ethics in it's curricula. It is essentially the antithesis of what they portray it as, but appealing to the average Germans ignorance (They don't know better- they've never been to Ft Benning or know those that attend, instruct or the curricula of this school) the media to include state run media had a constant anti US, anti intervention/War on Drugs, anti School of the America's message to it. Inevitable defeat/failure was an undertone in near all German media reporting regards the US intervention there, as in Iraq........ and yes the typical “this will be another Vietnam” flew around.
Over and over they talked about this, had TV shows, discussed it in radio, web articles etc. Flagrantly incorrect, you then had masses of “experts” that essentially used incorrect information (second hand reporting and analysis) as the premise of their further arguments. Whole web-pages devoted to this theme are still out there if you care google it! Knowing better, it's actually quite funny because of how stupid these people are and how biased the reporting was, but the greater point is that the Germans actually “benefited” from this even though they did nothing and actually worked AGAINST us and others. Even though directly affected oneself, not only did they not contribute, but they actually worked against those doing something because internally this was an issue that left oriented politicians thought they could exploit and after all, they don't need those stupid “Ami's” anymore.
Actions like this aren't moral, courageous, intellectual, cultured nor loyal, all various spins that the Germans try to apply to their worthlessness when they come out of the corner swinging trying to pretend like them doing nothing has a deeper reason other than freeloading.
But drugs, too, are internal enemy, because consumption is internal. Our mass culture is all about having fun at zero consequences, naturally we can think of nothing better than getting doped up. This is a good example of how we in America see every problem as a military one when we ought to see it as cultural. When I am in charge, Ft. Benning will teach how to deliver shock and awe to the Hollywood.