Being a reserve officer, I'll say you're totally correct. The units are in populous areas. When I joined the reserves, the unit did its own recruiting. They have limits. In my battalion in London, we had to turn people away from joining because we only had so much money every year to hire—to enrol people and pay them. Other units had lots of money, but of course they wouldn't share, because that's not how we do things in the military—or at least in the army.
You need to have the units in the areas where people are. I remember there was a time—I don't know if it's still true—when reservists could actually get funding, travel money, to travel to their unit for training purposes during the normal training season. I don't know if that still exists now or not. But for people to travel maybe 50, 80 or 100 kilometres, to go training every week, one weekend a month, that cost starts adding up and your pay is now paying for you to travel for you to do your work.