you clearly lack any knowledge of how a special forces or advanced recon unit operate .
firstly no ranks are acknowledged in the field , no ranks are worn . no ranks are mentioned over comms you would not pick out the officer unless you knew him personally and got close enough to recognise him . this is done to avoid the very situation you claim to carry out .
no ranks of any miltary unit even in standard units are mentioned in the field , if you did it wouldnt go down well as you make him a target .
its simply not done .
special forces do not operate under a strict objective , their objective is broad . they have far more freedom than a regular unit .
unless of course its a specific mission such as hostage rescue or taking a town or base etc .
but in the situation of an invasion a patrol would be placed in an area with the task of identifying military targets for future operations and engaging any high value targets , air defence , radar that sort of thing .
not go in gun blazing kill any enemy in sight .
thats the job of the conventional forces behind .
they wouldnt again the job of conventional forces .
it goes as follows
special forces deploy - identify targets for air strikes , landing zone to deploy troops , disrupt enemy communications , supplies and be a general annoyance
spear head units deployed - marines , paratroopers , armoured units
holding units come behind to hold and secure - bog standard infantry regiments
they were able to achieve this because as you said they were trained professionals , hathcock and his fellow sniper are the very kind of people you are suggesting civilians would pick off .
special forces operate in small units 4-6 men patrols , constantly concealed as hathcock was you would not catch them walking down the street my dear . you would not see them until they went loud .
its exactly the kind of mission and situation these units are trained to deal with .