It doesn't matter what manufacturer the program is vs the manufacturer of the hardware. When files are read they are read through RAM and accessed from there.
The reason for this behavior is because RAM is so much faster than a direct read from the device. If data is only read once, reading it directly from the device would be faster, but as soon as one small fraction of all the data is being read twice, RAM already outperforms. For that reason, it is a calculated action to always read through RAM.
However, drivers can access a device directly, and for certain actions, this is how it is being done, such as format etc. But then we are no longer talking about reading from the drive.
So long answer short, it has been designed to be read through RAM so caching cane speed up tremendously.
EDIT:
But... is it possible for a programmer to program it so that the file is directly read from the device, skipping RAM all together? Yes, if they program the driver part too and access the device on a hardware level. This, however, is a very difficult task to do, and in order to make it actually faster than what the system already offers is so hard (prone to bugs, crashes, etc) that its just not worth the trouble, and for that reason, its not being done.
Short answer: yes. Long answer: The data from the disk has to be read and interpreted before it can be displayed on the screen. It has to be stored in RAM as part of this process. – DavidPostill – 2016-01-22T18:50:30.240
What exactly is "child of OS" in this context? If you are asking if Windows Explorer, is special, it is just a normal process just like every other process. that runs. – Ramhound – 2016-01-22T18:54:56.903
From same manufacturer – Stefan Eftan – 2016-01-22T18:55:41.003
In this context, do you happen to mean, a system or kernel process? – Ramhound – 2016-01-22T18:56:26.663
i mean system, but now i notice that i missed kernel in process... But if wehave Software premission to ask System to ask kernel to give direct access to usb, that doesn't possible or for securty reasons not suitably? – Stefan Eftan – 2016-01-22T19:01:47.217
1What? Your last comment is confusing. You can edit your question to clarify what your question is exactly. – Ramhound – 2016-01-22T19:05:26.540
It is a non-trivial task to write an Windows explorer replacement, you can indeed replace the shell, with a third-party application. There are many third-party Windows shell applications that exist. You will just lose all Windows Explorer features by doing so. – Ramhound – 2016-01-22T19:19:55.937
@Ramhound you can also program a windows explorer replacement and just use the explorer API's to make it behave the same as explorer, just using your own appearance and add features you want, such as a tabbed interface, etc. – LPChip – 2016-01-22T19:21:04.960
I think the technical term for direct access to the hardware layer is/was real mode. More likely, the OP is looking for direct drive access or raw disk access – Yorik – 2016-01-22T19:46:14.183