Well, I am mentally leaving other magic off the table at the moment. I am willing to imagine for a moment that your average wizard is a butt, and wouldn't bother to stop for the literal minute it would take to help a stranger with a broken wagonwheel. Mend alone is world-changing.
But never mind that.
Like the PHB says, "not every acolyte or officiant at a temple or shrine is a cleric", and "true clerics are rare".
I would imagine even the rumor of instant healing would be enough to bring the peasants flocking. They would be camped out like they were trying to get concert tickets.
What's a good cleric to do? Step over the commoners begging for help?