That said, this generally allows optional fees - they just need to be disclosed, have clear opt-in and out, and cannot be profit centers for the landlord.
[1] https://seattle.legistar.com/View.ashx?M=F&ID=15702946&GUID=...
But again, if the advertised price must be the total price, it doesn't matter if there's a mailbox access fee or not. It's no different than if they eliminate the fee but raise the price the same amount. Make the advertised price be the highest price, and say "hey, you can advertise discounts off of that".
Nobody's going to advertise you can save $5 a month by eliminating your mailbox.
A similar effect, would be no longer advertising a plan's price if you enable paperless billing and autopay. You'd have to advertise the price without, and then can offer discounts for those things.
Or movie ticket prices being required to be listed with the convenience fee included, and if a theater wants, it can advertise a discount for buying a ticket some other way. More than likely that would just kill convenience fees.