Your example is not exactly what I'm trying to understand, but it's close. People recite their standard libertarian/republican/liberal talking points without a care for the vast number of times they have convenient "exceptions" or opinions based on rationale that is non-transferable to other subjects.
Time to make a second attempt at the thing I deleted earlier...
I think people believe that concessions in service of an ideal are pragmatism rather than hypocrisy. If the ideal society cannot be achieved, then it is better to compromise to do the best we can. In a consequentialist framework, this is philosophically consistent. The trouble is that libertarianism (and most formulations of liberalism) don't fit into that framework - they're rights-based instead (*). The rhetoric, reflecting the philosophical basis (or not), tends to be framed around 'rights' instead. Even though no one cares about political philosophy, the contradiction between 'rights' and 'doing-what-makes-society-best' is apparent, especially if the rhetoric isn't very precisely articulated.
The oversimplified version, in my view, is something like this: Libertarians want to start with the ideal of no government, and add just enough to have the 'minimal' size to keep society working. Liberals imagine a (large) government that secures the welfare of society, and trim it to keep society as free as possible. Whichever side you're on, you end up somewhere in the middle - the only difference is context, and who you irrationally dismiss as wrong.
(*) I don't actually remember any of this, so I'm probably wrong.
It gets much worse if you try to grasp the more leftist versions of libertarianism, many come from anarchist/communist/socialist movements that sprouted all over Europe in the 1800s. Many of these discard the more...unorganized thoughts of Anarchism (Bakunin's ramblings) and they tend to be linked with political philosophies that heavily criticized the communist/Bolshevik regimes or organizations, and now they tend to criticize the "Social-Democrat" thought pushing it to the right-wing field when many of this neo-libs are likely agreeing in part with the "social state" yet going for economic freedom/pro-private sectors.
They probably have a similar path from the American Libertarianism except in the opposite spectrum of politics. Like Wast said, they focus much more on individual rights/civil liberties and they see the decay of solidarity on the lower class through economic constriction. In their quirky way these vile creatures are anti-capitalist.
Many of these can be simply put as being anarchic for everything but the defense of basic rights...erm..social state then, in a way they are socialist who don't want a heavy regime taking over the strings, many embracing ideals that give more autonomy to small areas of territory so that there's less centralization and more processes of decision being public and participative.
Now comes the nuances.
Collectivist anarchism is pretty much advocates a territory is just a collection of participist communes where there's no actual land owners. People work on whatever there's to do and they get a say as much as anybody else. Very pretty but...erm...don't those weird religious cults in the middle of the USA kinda use a distorted doctrine similar to this?
Anarcho-syndicalism is similar to the last one except it's more like a "silent" proletariat dictatorship with local organizations to avoid any tendency to elitism and the creation of government.
Libertarian Socialism are the ones I modeled to make the beginning of this post, those ugly know-it-all bastards think they can create a society that regulates civil-liberties but then throw it all to the pigs by not having a centralized hierarchic government from which to run the territory. Instead they tend to think like the collective anarchists in which people can govern themselves out of necessity.
Mutualism is pretty much an anarchic society of entrepreneurs/creative people.
Anarcho-communism is the most Frankenstein of them all, yet one of the most successful historically, being one of the drivers towards the revolutions and their subsequent failures and demise of democracy in Spain, Italy and Russia. They are the reasons of the rise of dictators in these countries, and without WWII they'd have survived and likely still be a challenging force to it all. They all died tragically, either devoured or imprisoned by Bolsheviks, either bombed by Hitler's and Mussolini's bombers in Spain, or starved and skinned and stoned to death in Italy's lovely landscapes.
There are more nuances but "Libertarians" in europe kinda spring from any of these dark, shady, dirty corners. Now there is only world guru,
Noam Chomsky 
