The Row Selected by User even it not fired due to the fact that an individual row is not being selected by a user.
Usually, a separate button or event will be used to determine how to handle the data if all are selected. One important question to ask is whether or not the table is paginated. If the table is paginated, the developer will either handle the All Selected for only the records on that page, or will use the bound data to manipulate all records.
We have had custom applications in which we replace the Select All checkbox with a link that provides custom logic.