I see a whole lot of mail returned to sender for being abandoned, or being discarded for being abandoned, in those communal mailboxes. I also see a lot of people only visiting their mailboxes weekly, like how they take out their trash cans for the truck to pick up, so mailboxes will be even bigger targets for thieves as there'll be more payoff for the effort than before.
2/3 of Canada have been on the system for years. Any new developments in the past 10 have had this. None of the problems you mention are an issue.
Not to mention any small town - my parent's town *celebrated* when they got the communal mailboxes, because that was an upgrade from having to go to the post office during normal business hours to pick up General Delivery.