By default, "user" group doesn't have access to ulx voteban for just that reason... it could be abused.
Voteban is intended as a means to allow an admin (default group that has voteban access) to start a voteban to allow users to have their say whether or not anyone should be banned, including other admins/superadmins/higher groups if needed.
Adding the can_target check to voteban would prevent that from happening.
If you have "user" access group abusing voteban privilege, don't allow "user" group to have full access to it.
Give full access to admin or other trusted group only.
Then, if you just must give access to users, restrict the time allowed as indicated.
If you're having issue with ALL the vote commands, then you have an inheritance tree issue somewhere in your groups, and while an affected group member is connected to the server, need to attach the file created from the server console command "ulx debuginfo" to your next post.
