That's because they are different, police can come with a warrant to check your house for illegal activity but they can't monitor you remotely 24/7 with barely any human intervention and store everything you do indefinitely. With electronic communication you either get full privacy or none.
And no, putting company's in charge of your privacy isn't a solution, if they can be compelled to give away your communication history then they'll abuse it. Have you not learned anything from the Snowden leaks?
Police got a warrant for Durov and arrested him. How is that different? Yet some people are upset anyways.
And it's not true that with electronic communication you either get full privacy or none. You can have end-to-end encrypted messages with unencrypted metadata, so that when police observe a message implicating the sender in a crime (e.g. on an arrested suspect's phone) they can get a search warrant for the IP address or phone number associated with that account and then visit the owner in person to look at the messages on their phone. This doesn't allow police to read everyone's messages all the time undetected, but does allow them to read specific people's messages if they get a warrant.
Since Telegram doesn't only have unencrypted metadata but also plenty of unencrypted messages, there must've been many cases where a search warrant would've yielded lots of useful information. If Telegram didn't properly respond to all warrants, it seems fair to launch an investigation.
According to the Telegram FAQ (https://www.telegram.org/faq#q-do-you-process-data-requests) data on their servers is encrypted and the keys are split and stored in different jurisdictions (and different from the jurisdiction where the data is stored).
With such a setup what does it mean to comply with warrants? Are we saying that Telegram should voluntarily yield all information regardless of jurisdiction?
Ah, this multi-jurisdiction setup explains why Durov himself was targeted. As the presumed controlling entity behind that network of shell companies, serving him with a warrant seems like the most effective legal means to make Telegram comply.
And no, putting company's in charge of your privacy isn't a solution, if they can be compelled to give away your communication history then they'll abuse it. Have you not learned anything from the Snowden leaks?