I am not defending it's use but a secret program is a targeted program, you can't use it in sweeping arrests without parallel construction. Whereas with an openly existing program you can point out that someone has been talking to their friend about how to get abortion medication and arrest them.
The real issue with 100% enforcement of law is it requires a society with differing values to not just agree on which laws exist but what just punishment is. Without leeway for differing social judgement or bifurcation.
Parallel construction is incredibly easy though with confidential informants and honeytraps/entrapment (for another crime, for example).
These are just excuses to convince yourself that what the US is doing is "not bad" but what India is doing is "terrible".
Both are doing similar things. You have no idea what the US is doing; I have some inkling, and it is terrible.
At least India is publicly disclosing what this app does, and that the phone has this app. Do you have any idea what the US does?
Hint: that big data center in Utah, what is it for?
Another hint: the US has given many billions of dollars to US telecom companies under the guise of "rural broadband" and "rural cell service". Has the state of rural service really changed much in the last 30 years?? Why has all that money been given, then?