It might sound surprising but it makes a lot of sense to have different standards supported over USB-C. USB-C is just a form factor of the connector.
For USB 3 or USB4 speeds you physically need more wires in the cable, while for USB 2.0 you only need 5 wires. Also if you want really high data transfer rates of 40 or 80Gbit/s the cable can only be around 1 meter or 3 feet long.
So because USB-C supports different USB versions, a charging cable can simply be USB 2.0 and be cheaper and long and do it’s job just fine.
If USB-C was only USB4 it wouldn’t be all that useful. Devices like wireless mice or DACs or game controllers wouldn’t/ couldn’t use it and the cables would all be thick and expensive and short. And for charging regular things we’d still be stuck with micro USB.
The only downside is that, yes if you are doing a thing where you need high speeds such as connecting a screen or external disk to a PC you do need to check that you’re using a high speed cable, but pretty much all good quality fast cables have the speed printed onto the connector housing.
But yes the iPhone restricting speeds to 2.0 is strange and most definitely just a trick to sell more pro models. There are plenty of devices that simply have no need for anything besides 2.0, be it because they send no data or just very little. But phones really aren’t in that category.