When you install the app they steal your contact list and populate their database that way. Most people are unaware of this, or don't care since we are a third world country and privacy is seen as a first world problem. The vast majority of thinking here is not very sophisticated about these types of topics. Only a very tiny fraction of the total population is averse to sharing personal information like phone numbers…
My wife installed TrueCaller on her phone. She is technical but not a developer. I asked if she knows they steal your contact list and spy on you and her answer was “so? It’s just phone numbers and names and they need to get the data somewhere as they are providing the service for free” I live in a developed country and we have a high standard of living. Giving this anecdote to illustrate many people genuinely don’t…
Fun fact: Elector rolls are public record. Your address is already out in the open.
> Giving this anecdote to illustrate many people genuinely don’t see TrueCaller’s spying as a big deal.
That's because it makes no material difference to them.