Why temdb and log file size is not reduced by SQL Server
Shrinking a database is not a good idea. There are specific cases, but they require a DBA to carefully evaluate the situation.

Sql Server cannot have an idea if a query in, say, next five minutes is going to hit tempdb heavily. Without such a knowledge, shrinking and expanding tempdb is going to be unnecessary and, to be honest, stupid too.

TempDB is re-initialized whenever Sql Server service is restarted. In most of the cases, this effectively shrinks the tempdb data and log files.