Why do most rechargable/smart/small electronics items come with AC adapter instead of USB-C?

[Denly]

Like why? I can't imagine an AC adapter cost more than a USB C adapter by much. Of all my small electronics in the household, most come with AC adapters instead of USB. clipper/smart displays/cordless phones/router/small switch/sonicare.....the list go on. So instead of 1 good USB charging station that power all in the same area I need a big ass power bar to fit all the AC adapters.