Here's the deal.
It's expensive to stay on high alert all the time. All those extra guards, guns, maintenance, etc. That costs money. Up here, after 9/11, we maintained high alert at the bases for a couple of years, then decided to go back to more-or-less before. Not quite; back in 2000 I could walk onto the base only flashing my ID, and once I did show a post-it that said PASS on it. As it stands now, I do require an actual valid pass to get onto the base. However, the security on the base itself is lower than that of my local YMCA. (The base passes are easy to forge and don't get scanned or recorded; the gym requires an active membership and records your entry times.)
What I'm getting at here is that when you're on guard duty at the War Memorial, you're there to be a meet-and-greet kind of soldier. The only shooting you're expecting is some selfies with the kilted guy (meaning you) and maybe a couple of shots at the bar after work. You're not guarding anything. It's a public sculpture that's maybe 50 feet per side. There's literally nothing there to defend. (I've been there a few times; years ago for work I stayed at the Lord Elgin and worked in the next-door building, housing some PW stuff.)
Now, here's the other thing. Bullets. You have to track the shit out of them. If you gave the guards at the War Memorial live ammo, it would be a complete clusterfuck. If you're giving someone ammo, you're expecting them to get shot at, right? Which really means they should be wearing armour as well, not the ceremonial dress uniform (which only offers protection against thrown bullets) So you've got to get them armour, bullets, and a real gun, plus track all that stuff from day to day. What if the gun got dropped and discharged? What if you stopped for a picture and someone took your gun or cut themselves on the bayonet? What if the magazine fell out and the ammo sprayed all over the ground? Now the person guarding is presenting the image of a drunkard scrambling around for their car keys in the dark.
Weird scenarios, but all significantly more likely than a schizophrenic walking up to you and shooting you in the back in cold blood on a boring Hump Day morning.