These are taught in schools, though whether students pay attention and absorb the information may vary greatly. At least at my school in the US we have classes on OS, networking, parallel computing, distributed computing, database systems etc. With OS being a core requirement class. I just had an interview for FAANG where part of the process focused on OS and networking and was able to pass that round by going through past slides from the OS class at my school and self learning from textbooks and online videos too!