USB flash drives eject issues

[bk7777]

This is more of a general question related to the false indicators Mint 17.1 Cinnamon gives when ejecting USB flash drives.

If I have been loading gigs of data on a flash drive. I get the progress bar if the copy taking place (normal). However when the progress bar says it's complete. and I eject the flash drive. It shows me that it is ready to be pulled out of the USB port.

You take it out and it gives you messages about can't right to /dev/sde. All indications were that the eject completed correctly and could be removed.

I later learned that lsblk showed that it was still connected for as much as 2 or 3 minutes after the eject showed it completed.

I am assuming this is related to buffers having not finished flushing. When I copy large amounts to data to flash drives. it usually shows about 800MB copied in no time then starts getting real slow especially USB 2.0 devices. in the beginning of the copy operation it shows like 150mb per second transfer speed. By the time it gets to the end minutes later it's down to 10mb per second.

So here is my question why can't mint correctly indicate that it is really safe to remove the flash drive, when lsblk shows that is isn't. As long as lsblk show the flash drive in the list it is not safe to remove the flash drive.

2 are there other commands that can be used like lsblk to give more detailed information like how much data is left to be written before it unmounts?

Thanks,
Brian