Why are these Hidden in my external Drive? Spotlight, Trash, Time Machine and Document Revisions

Simple answer is that they are hidden so you don't mess with them. Each one serves their own purpose. I can offer insight into some of them.

• .Trashes - When you delete a file it still remains on the drive until you empty the trash. The files will be located in this folder until the trash is emptied.
• .com.apple.timemachine.donotpresent - You were asked if you wanted to use this drive to back up your data and you replied Don't Use. More info is available here: How to stop Time Machine from constantly … - Apple Community
• .Spotlight-V100 - Is the index of files and folder used for searching. Any changes you make including clearing this data is done using the Spotlight options in Settings, not by changing anything with this hidden file. Rebuild the Spotlight index on your Mac - Apple Support

A more complete and perhaps better explanations of each can be found here:

https://eclecticlight.co/2021/12/09/hidden-files-and-folders-on-apfs-volumes/