"avtar" (w; we would have totally spelled it "Awatar" - I see you Cameron) and "vikas" (v; something our PM got us loads of) have two distinct व sounds and it is phonetic and we don't have to memorise it when we make these sounds. The problem is English keeps coming to us over the years while we take our sweet time in getting used to this pronunciation and spelling monstrosity. Another reason could be, not everyone went to schools where English with strict pronunciation was a focus or even a nudge.
This was to your
> I don’t know why
And I don't know where you are from but if you are from the "English west", I am pretty sure you mispronounce "Gandhi" like "Gendi" or "Geyndii" and been doing it for decades without bothering to even learn it. "I don't know why" :)