you neglected to mention that US non-governmental aid generally is far in excess of governmental aid to most nations -- and it mostly goes with no strings...

Private giving for developing nations is $71B of which $47B are personal remittances to said developing nations; subtracting those (which BTW, are an economic loss to the US but are accepted here with virtually no limitations), there's still $26B in aid compared to the $25B of official USG aid, about a third of which is military aid (and over half of that in the bribes to Egypt and Israel thanks to James Earl Carter). So in non military aid, that's about one and a half times as much no string aid as that with the expectation -- but rarely a demand -- of purchasing US goods.

People can be and are altruistic; governments by and large are not -- they generally act in their interests. Which is what they're supposed to do...