Currently, it is not possible to run net usershare list or any other net
command as nonpriviledged user.

$> net usershare info
Failed to init messaging context

According to strace, it fails when trying to create a lock:
open("/var/lib/samba/lock/msg.lock/18128", O_RDWR|O_CREAT|O_NONBLOCK, 0644) =
-1 EACCES (Permission denied)

$> ls -ld /var/lib/samba/lock/msg.lock
drwxr-xr-x 1 root root 40 Jun  7 12:26 /var/lib/samba/lock/msg.lock

$> rpm -q samba samba-client
samba-client-4.6.3+git.25.0c154becb13-1.2.x86_64
samba-4.6.3+git.25.0c154becb13-1.2.x86_64