It's not completely true that it is not Greek. Yes, it is IPA, but they needed so many symbols for IPA that they borrowed from Greek for some of them.
Many of them,
⟨ɑ⟩, ⟨ꞵ⟩, ⟨ɣ⟩, ⟨ɛ⟩, ⟨ɸ⟩, ⟨ꭓ⟩, and ⟨ʋ⟩
have different Unicode characters, but are Greek for practical purposes,
is a actual Greek Unicode character, and
⟨β⟩ and ⟨χ⟩
are usually represented by the actual Greek letters though they are not supposed to be.
This is described in Wikipedia.
Some of the modified letters look as close to Greek letters as to Roman ones:
⟨ʋ⟩ ⟨ʙ⟩, ⟨z⟩, ⟨ⱱ⟩, ⟨ɵ⟩, ⟨ɛ⟩, ⟨ɜ⟩, ⟨ɤ⟩, ⟨ʏ⟩, ⟨ʊ⟩, ⟨ɪ⟩, ⟨o⟩, ⟨ʌ⟩
So, taken all together, and from the point of view of someone familiar only with the Roman and Greek alphabets, it does appear to have a significant proportion of Greek in it.