not always. you are not considering the extra space/expense of running hot and cold pipes all through the building. and the wastage when you run hot water at 3am to get to your hot sink and all that hot water that goes cold in the pipes between your 12th floor unit and the tank in the basement. just to bring to you 0.5 litres of hot water to wash your hands for 6 seconds.
You're already running all the cold pipes all over the place, and the hot pipes in the unit so really there can't be much more expense to run a main hot pipe. And it's a one-time expense. And to your second point, that's what recirc systems are for. I wait less time for hot water in my condo than my friends do in their houses.
The bill for hot water is astronomical in the condo I own that uses central systems. People waste way more when they percieve they don't pay directly for it.
There's no 'hot water' bill. It's comprised of water and gas or electricity. Considering water is almost never metered individually, it's a shared expense already.
What's the cost of hydro for a 40 gal electric tank for two people?