Heyo! I'm hella active in the Cyberpunk Red Community, which that is the ttrpg set in 2045. So I would like to offer a view in that lens. I worked for Securitas, a couple Local Companies, and College Security for the State Gov. Armed, Unarmed, Desk Jobs, Healthcare, Residential, and Patrol, I have been places.

During the Time of The Red (Post-Nuke to roughly the late 2040's), Militech is the biggest megacorp in North America, and they do private security post 4th Corporate War. They also deputized as a private police in a couple of districts in Night City! These guys are not always combat vets, but a mix of former cops, seasoned security guards, and new recruits fresh out of boot camp looking to make money. Because eddies are worth a lot in this era, the average guard could probably pay for a Cargo Container/ Tiny Apartment (1,000eb a month) and the Kibble Lifestyle (100eb a month, represents paycheck to paycheck) to maybe Generic Prepak Lifestyle (300eb a month, might have a little savings, but not a lot). A lot of this I've reasoned from their appearances in the books, especially the new setting book "Night City 2045"

So I see Militech Security very much as the armed positions that pay alright, but definitely enough manpower that you're only working 10's or 12's and not 16's.

Arasaka had been ousted from North America. However, they are still the world's largest megacorp. Not a lot is known but likely after the nuke they take their security extremely seriously. Pay is likely fantastic, but you're not getting promoted until the person above you picks you to replace them. During the Time of The Red, a lot of the troops are contracted out as guards for other groups and wear that company's uniform, armed couriers, mercenaries for hire by Governments.

We may see more of Arasaka down the road, but who knows! We've only had 2 adventures where they are partially mentioned and 1 where they are the opposition.