Fast charging is a luxury, not a necessity.
Apple provides you with the necessary brick to charge it.
If you want charger, you’ll have to get it yourself.
With millions of devices sold per year, it’s not something I see Apple feeling the need for to include it.
Especially if you think that even adding a normal charging brick is not even necessary for those who already have an iPhone in use.
I have like 6 or 7 bricks lying around somewhere in my house and only use two off them, of which one is an iPad charger that I bought myself and a normal charger on my bed stand.
If I were to resell my iPhone or Apple Watch, I’d simply keep the iPad charger and keep use it.
TL
R Apple already has fast chargers for sale, no need to keep including them with each device sold