USB C has a power delivery spec that permits increasing voltage above 5V; in order to do that you need to negotiate what each side (and the cable, too, I think) supports before increasing voltage. That's how laptops that use much more than 10 W can use USB C as their charging port.

But that's only for high voltage charging, right? You can still get 5V without negotiation, if I understand correctly. If so, that's a tradeoff I would be perfectly fine with.

USB-C is being used to power things where 5V is not remotely sufficient. So while for some devices (cell phones, largely) 5V is a plausible tradeoff, I don't really see a world where many MacBook / Chromebook / etc users opt for 5V max charging power.

Fair enough, but I was really just talking about safety when using public charging points, which implies smaller devices. Also, I was really talking about what I find acceptable. Other people's mileage may vary.

Yeah, but BigCo can't charge you $20 for that no-data-passthrough cable.

Doesn't USB require the data connection to allow it to negotiate higher than the base power level?