I think there should be some use of the “moral sphere” model in understanding the dilemma presented. The moral sphere is conceptually easy to understand—each person extends moral consideration varying from the center, oneself, outward into society(or world in whole) until a boundary of moral exclusion is reached, and beyond this boundary exist ‘them’. The model would thus have Buddha being an idealized moral example having no boundary of exclusion and no decrease in moral consideration from self to the rest of the world.
The next consideration is that of culture, here in America, where we have schooled everyone to be...well....pitiful bitches. Seriously, the schooling process both breaks down community -even sense of community and neighborliness—and creates drones waiting for instruction from authority. (school is designed to do this see John Taylor Gatto and Ivan Illich for history and arguments). The studies you cite (and the fact you used deTocequville who witnessed the US pre-compulsory schooling) indict the culture created by our adoption of a school system meant to create a compliant, mindless, consumer society. To really impact the level of altruism in our culture you would do what you could to steer people away from the school system.
As for immediate intimate remedies look at how your “community” is structured—is it a really community(holistic relationships) or just a network(conditional, purposed relationships), or worse a hierarchical structure (relationships at work)? A final consideration is that if you are conditioning yourself to be more responsive in helping and more considerate of others you are going to find yourself developing skills in asserting authority, taking charge, and trying to solve dilemmas where you are being compelled to sacrifice from your own ‘good will’, or whatever tune your heartstrings get played to—this is undoing what schooling trains into everyone in various degrees.
The basis for honesty are arguments for development of a an egalatarian relationship. If the relationship is not based on equality then dishonesty is an inevitable result in resolving moral dilemmas. In the example case there is no reason to consider whether or not deception in words should mirror the deception of hiding filthy Jews. To split hairs further the ability to convey the truth is absolutely impossible in language. The allusion of of the 1st quote is towards this understanding: anything contained in language is only an approximation of the truth. So how honest can we really be?