Yeah, ‘True Good’ versus ‘True Evil’ reflects how I see these too.
What ‘Neutral Good’ really means is someone who optimizes between Lawful group identity and Chaotic individual identity, whichever can achieve the most Good possible. This ethic is pure Good. ‘True Good’.
Moreover, the identity axis (Lawful versus Chaos) behaves differently from the ethics axis (Good versus Evil).
In the ethics axis, the default is a mix of Good altruistic sharing and Evil predatory theft. Doing only Good while also figuring out ways to sustain each other by Good means, is a difficult situation to achieve.
By contrast, in the identity axis, the default is either Lawful group identity or Chaotic individual identity. The ability to make these principles work together constructively is a difficult situation to achieve. For example, in Daoism, the Lawful principle (Yang) conflicts with the Chaotic principle (Yin). The True Way (Dao) is to balance these two principles in a kind of dynamic equalibrium to nourish and nurture each other. Similarly, in the Middle Path of Buddhism (between self-abnegation and self-indulgence), and in the Golden Mean (between others and self) of various cultures, including Judaism and Christianity, the True identity is both Lawful group and Chaotic individual. But this True identity is spiritually difficult, and takes great effort to achieve and sustain.
In the context of D&D, an annoying misinterpretation of alignment sometimes emerges. The error is, somehow Lawful Good is more Good than Good. Obviously, Good is as Good as Good can get.
If anything Lawful Good is less Good than Good, because where lawfulness and goodness conflict, the hero who promotes both must compromise.
By referring to the alignment as ‘True Good’, it helps clarify, the one who strives for True Good does the most Good possible.
The hero can empower the group to do as much Good as possible, and the hero can empower an individual, one-on-one, to do as much Good as possible. This harmony between lawfulness and chaoticness - where all things work together for Good - is a tricky ideal to achieve. True Good.