Is there a reason why Postgres doesn't have Byte or tinyint?

According to the manuals, Postgres has smallint (2 byte), integer (4
bytes) and bigint (8 bytes)..  I use a lot of structures with "bytes"
in my code and it's kinda annoying to cast DB output from Int16 to
Byte every time, especially since there's no explicit cast in .NET and
you have to use System.Convert().

Is there a work-around, or do people just cast or use Int16 in their
data structures?  Just wondering..  I know on modern computers it
probably doesn't make any difference anyway..

Mike