errorlog and tomcat connector

Scenario: Apache 2.0.52, Tomcat 5.0.28, RHELinux 4 , Jakarta Tomcat
Connector 1.2.15

With a default/standard configuration, when a request handled by tomcat
returns an error (http error 404 or 500) it doesnt get logged in the
apache error log.

As far I as could see, the only way to have those errors logged is in
the tomcat log, JkLogFile, changing the JkLogLevel setting from the
default (and recommended!) value.
This seems odd to me: the separation that Apache mades in a "normal
access" log and and "error log" is logical: the first is typically
huge, oriented to batch processing; the later is small, and is useful
for (manual or automatic) monitoring.
Am I missing something ?
What do normal people do to monitor access errors in this scenario ?