Create a SharePoint option to disable the "SHARE" button, giving people access to site.
A Sharepoint user with Edit permissions on the company "Finance" site was only supposed to share a folder named "Invoices" that is located in a library within the Finance site. She highlighted the Invoices folder, and instead of selecting the three dots to the right and selecting Share, she clicked on the upper right-hand side of the site page and selected SHARE which shares the entire site and it's contents. Six users were sent that shared site link but only one user accessed the site. In the site are very sensitive financial records like employee salaries, owner bonuses, legal financial docs to name a few. Luckily only one user snooped around. Even though a group named "Finance Members" are the only ones who can access this site, once it is shared by one of the members, the invited users have access to all of the folders and files within the site. This was quickly resolved but there must be a way to completely avoid this from happening again. We were luck to catch this 15 minutes after the invites were sent out.
Looks like this has been reworded to Share Site now, which should solve some of the confusion.