The examples are just examples, the uses in the tree are different. For example, ksh doesn't exit if pledge fails, it just prints an error about why it failed a

The examples are just examples, the uses in the tree are different. For example, ksh doesn't exit if pledge fails, it just prints an error about why it failed and keeps running (imagine how fun it would be the shell did just keep terminating). Other programs use their own logging to report the error, for example httpd logs the error the same way it logs all other fatal errors before it exits.