Is it possible run squid-windows service on 'Network Service' Logon ?

[MORI-HAMAMATSU]

I installed Squid-windows and confirmed it's running on 'Local System'

I want squid run on 'Network Service' to minimize access permission.
I changed squid-windows service 'Network Service' Logon. It did not work.

So I changed the owner of Squid directory to 'Network Service' and add Full Control and it worked.

Question
Please tell me a reason that Squid-windows service is running on 'Local System' Logon (Not Network Service Logon)