You have to calculate the amount of data provided from all users in this case + storage + processing power to do all of that. It’s probably more than you would expect too.

The second point is why would a company do that? If the NSA or whomever wants to snoop on you, they’ll drop malware on your phone, subpoena your iCloud backups etc. not try to coerce a company to record people’s conversations when said company has no desire to do so.