I saw some photos of those ads on twitter a few years back about a certain manufacturer's engine being the correct choice for a specific in-development military plane.
It's weird seeing physical advertising be so targeted. Like, multiple physical ads to target less than a dozen people total.
It's a little broader than that, because these are general defense contractors who have their fingers in every pie. So it's seen by contracting officers, partners, potential employees, etc.
It's a bit like a Coke ad -- you do not need to be informed about Coke, but it creates an atmosphere of nebulous positive feelings. Still, kinda weird.
It makes sense though, given that those dozen people have decisive power to bring billions of dollars in revenue and decades of work to the companies advertising.
Like, the Dutch airplane manufacturer Fokker went bankrupt and stopped manufacturing planes in 1996, but the brand and company are still very much alive, manufacturing parts and providing maintenance services to all their planes still in operation worldwide.
You're not but there may be people that are. Besides, tanks are cool and I'd go to shows like that for entertainment purposes. I went to the Dutch military museum the other day, it has a Leopard tank outside (and of course a collection of tanks and the like indoors, including a German V2 rocket suspended from the ceiling).
There is something deeply sinister about seeing a defense contractor building in and around DC. Very nondescript 80s-90s dark plexiglass office box with a parking lot. Only with metal fencing, coated in cameras, anti ram bollards, and an armed guard at the gate, plus no doubt other security measures we can't see. The most secretive cutting edge science on death and killing being performed in the most otherwise happy go lucky seeming 90s model suburbia where there seemingly aren't any poor people around at all. Something deeply dystopian about this model utopia optimized for an ever present and unstoppable war machine.
If your preparations for war are influenced by advertising in the DC Metro, you are not a serious professional who the public can trust to desire peace.