I don't know about the USA but the rest of the world
has largly moved to regulated SMPS for small device
wall warts. And they generally even suport the USA
voltage too (Wot is it 120 volts) ;-)

Conventional external power supplies using bulky 50/60 Hz line transformers
have largely disappeared, as the parts used in switching supplies have
become less-expensive.

Most products come with tiny high-frequency supplies that are not only
regulated (regulation is a native feature of switching supplies), but will
work on any line from 90V to 250V. This allows the manufacturer to have a
single inventory. The same supply is shipped to every country, with only a
simple plug adapter (where needed).