Grep is inefficient search engine, because it needs to scan through whole content (and Telegram uses search indexes). Also, grep cannot deal with words forms and inflections (you type "foot" and you also want to find "feet"). Inflections are not very important in English, but you need to deal with them in other languages where the word can have many forms.

Not at all. Try searching 500/1000 sources (maximum number of conversations any free/premium user can be part of), each with potentially millions of messages, and providing the results in under a second.

So interesting. I just did a search for mentions of someone I know in multiple Telegram groups and channels, and got all the results, going back 5 years, instantly. And these groups and channels have millions of messages. All media is also perpetually available (unless deliberately deleted), and take a couple seconds to load. I don't see any other platform having that kind of convenience.

Yeah Telegram search is not in a state where anyone should be proud of it.

Advanced math is actually more difficult (in my opinion) than programming languages.