I would not count on usb plugs being ubiquitous. They are pretty common bedside at nice hotels, but I wouldn't count on it at small motels in the back country and certainly not outside a motel (restaurants, gas station).

*edit: I saw advice somewhere that suggested having a small splitter in case more people are trying to use an outlet than plugs available.

Something like this: https://www.amazon.com/Extender-TESSAN-A...0NsaWNrPXRydWU=