One thing I liked about 3e, though I didn't really use it, is that they at least had a method for establishing how many members of each class existed. The first population centre that could field a 9th level cleric was a large town which had a population of 2000-5000 and then you doubled the number of each level below (2 8th level, 4 7th level, etc). While this might seem to mean that there were a large number of adventurers kicking around since you rolled to find the highest level of each class to determine the total number of members of each class, this was using a completely different system where NPCs were built as PCs, they may not have actually been adventurers instead gaining a few levels after years of working in the local temple or as town guards whereas now NPCs are simplified.
Some things I'm not so sure I'd worry about is members of a different faith. More likely, the faith is following the same pantheon of gods, not a singular god. You might have a patron god that you pray to most often, but you're likely following the same pantheon as the rest of your people. That means that a dwarf who has Clangeddin as his patron is still just as likely to be raised by a priest of Moradin, an elf however, is not.
That whole thing where you must be willing to return is an odd requirement in that if you have reached your version of heaven, would you really want to return? If I died and my soul ended up in an eternal paradise, I'm not coming back. DnD is bit different though, we have raise dead spells for a reason so I guess if you still feel you have work to do amongst the living, such as slay that dragon that's been bothering the country, then you will be more willing to accept resurrection. A merchant or farmer (who has somehow managed to pay for this insurance) might be less inclined.
I also like to think that priesthoods aren't running some insurance scheme to raise the populace, I certainly don't think that the sole 9th level cleric in a large town is wanting to run around raising the dead everyday, they are likely the local leader of their church and have more important things to do, though if they are Orzhov then maybe this is exactly part of the service, other than them, I'd say that raising the dead is reserved primarily for the wealthy (I include adventurers here since they often have more money than some kingdoms), nobles, and aristocracy, perhaps they have a time limit so that if the king dies and no one can raise him before sundown the next day then he stays dead and the heir to the throne takes the crown.