They supply a charge fine, but no standards-based fast charging.
USB Power Delivery 1 was a disaster, launched years after Apple had moved beyond 7.5W charging. Android phones typically also ignored it, using Qualcomm's proprietary charging tech.
If you want fast charging, use the bundled USB-C cable to charge your iPhone rather than the USB-A ones from years ago.
To flip it around, what advantage do you think one gets with official Apple iPhone chargers? Do you know of any evidence that Apple promotes their chargers working better than others? And if none exists, why would they sabotage customers who were never educated that hypothetically only Apple chargers charge fast?
So not fast charging, charging at all. They work on some of the iPads, so they do work.
Why do the phones refuse to charge then? Not fast charging, which I can sort of understand, charging at all.
And Lightning has been charging my iPhones pretty fast
"Many different standards" means "no standard".
> that apple just ignored.
Apple ignored them because none of them were standards until very, very late
But please, reference a USB2 or USB3 standard over a type A connection that enables fast charging too. This will be fun.