And again you forget that we are not talking about you, or I. We are talking about young and/or inexperienced players and DMs that are discovering the game. What is old and lame for you and I is fun and exciting for them. But only if there is something to do with the rewards.
I recall using the
PCs accompany the caravan as guards trope
once, in my second year of GMing. The PCs were 5th or 6th level. And the reward had nothing to do with it - the players had their PCs accept the task because it was obviously the adventure that I had prepared. I don't remember what the promised reward was. But I'm pretty confident that the promise of an extra 100 gp, or even 1,000 gp, each wouldn't have made any difference!
A god giving a quest is a classic trope used in legends, literatures and mythos. You may not have gods or have downgraded their importance in your campaign world. But it is not so in every other campaign run by other DMs. In many campaign worlds, the gods are very much important and pleasing your patron deity (or the one of your cleric) is a good thing to do.
Last time I checked, the 5e D&D rulebooks had gods mentioned in them, a whole appendix worth!
Whether or not clerics need to worship gods is neither here nor there: I played AD&D games where there was no cleric PC, and was able to frame situations and generate interesting play without needing to boss the players around with threats from patron gods. As I posted, that was considered bad play back in 1990, at least among me and my friends.
Old DMs like you and I do not need the tools to do our job, we are way past these artifices. But beginners, especially the DMs do need them but they got removed.
To me, what you seem to be lamenting is the lack of techniques like gp-as-reward-system or gods-as-quest-givers-that-players-can't-refuse, which in some circumstances might help paper over the fact that the players don't care about the GM's fiction. I choose the words "paper over" deliberately - because if players, for whatever reason, think the situation the GM is serving up is uninteresting, then there will be issues and dangling gold or gods in front of the PCs won't change that! If the campaign is boring at level N, it will probably still be boring at level N+1, or at level N but having spent 100 gp on a healing potion, etc.
Hence why my advice to new GMs, first and foremost, is
always use your best material and
present interesting situations.