Path bug with Debian as root.

I noticed a bug in Debian 10.4 https://www.debian.org/News/2020/20200509 where certain commands are not in the root path by default.

Example;
adduser which is in /usr/sbin and as root adducer is not found.

Of course you can do /usr/sbin/adduser but which kind of looney would be wanting to do that.

The above can be seen when doing su and doing su - gets around it without modifying anything.