This was fixed in Bug 6357 14-May-2009 and was then reverted 05-Jul-2009. Instead of using popt_common code, net is using it's own option parsing that is almost, but not quite, identical to what all other samba tools are using. net commands require usernames and passwords on the command line which is a security risk for some organizations. net needs an --authentication-file option.
samba-4.15.0